Ok you admitted at least that your source is kinda very “different” from all the other sources i found on the first 2 google pages on the internet. I appreciate it! That shows me that you dont deny facts allthough it seems that you dont like to think about other points of views. Nevertheless It is a base i can work with 
So i will use some time to explain my arguments in more than 30 words because it is
nearly impossible to make a point clear in few words. This is especially the case when you have to explain game philsophie.
This is a question of game Philosphie/Game Design. I like game Design which is more like d2/poe much more. To my mind it is far superior to the current game design choices in d3 in the Item Department. I mean the Game Design choices in d3 are in some areas interesting for me ( if they wasnt i wouldnt have played d3 so much) but in the area of itemisation the development of d3 is from my perspective just horrible. I can explain you why.
1. Variation of Items and rarity
The core of every ARPG in the world so far is to play the game to Progress and to make a character stronger. It should feels fresh and you should feel the Progress of your character.
Most games use for that purpose items. And in nearly every game the most fun aspect is to farm for fresh and new items.
In d3 the game makes the items raining. I mean 150 per hour of the strongst class of items (I dont speak at this point about quality like ancient or primal i speak of legendary/sets basicly)? I understand your point. I see that Item rain is basicly not that bad! The Problem is that you have the absolutly same Item in 3 different qualities.
I mean in season the game barely throws a full set at you! From lv 0 till full set you need less than 15 hours without even rushing the game. I mean what is the purpose of fresh and new gameplay when the game is literly throwing the items at you that are making the game fresh and different. in d2 you farmed ~30-40 legendarys with a highend mf sorc too. The difference was that there wasnt the same item in 3 different qualities. every quality of items had its own drop rates ( and in every Quality there were more or less usefull items. For example SOJ was normal the lowest quality of items but it was by far the best item for most caster builds ) and even in the same qualities some items were more or less likely to drop. The items of very rare quality werent extremly stronger than the items that were more common.
I can give you an example. You wont understand it exactly if you hadnt played d2 but as you said before that you had played it for 10 years, you will understand it. There was a javelin build for amazon with the item titans revenge. It was lightning based and had a unique play style. There was an Item for the bow typ of amazone of same rarity, it was called “the buriza”. A titans revenge build was ~ 30-40% stronger than the buriza build in damage( single target). The buriza build had better aoe damage and was safer and easier to play. And there was the unique item the windfore. it was 1000 times more rare than titans revenge ( i guess havent exact figures). I found 1 in around 3 years. my point is, it made the bow ama build like 40% stronger than the titans build, even in single target damage. For me because i was a min max guy it enabled a new build and new gameplay and I felt great. The bow build had basicly better aoe and more range, the Ama become because of the windfore something what you could consider “op”. Even though, there wasnt a demand for nerfs because this build wasnt better in every situation (nerfing was uncommon too). For example: The WF-Bow Build was useless against physic immune enemies. And the other point was that the item was so rare when i found it in first 2 Weeks of the exp , it wasnt duped at all i guess. I got extremly offers for it like 300 dollar but i didnt wanted to sell it. i had the feeling to have achieved something unique and was joyfull for around 2 weeks.
Such an itemisation is to my mind a good and very entertaining Itemisation. You dont farm for basicly only stat increase of your “normal gear” what can be fun at some degree but additionally for that extremly rare and cool item that can change your gameplay completly!
2. Progression and Gameplay
In world of warcraft the itemisation-system with that “+ 10% stats”, where you got your items pretty easy and run threw the item loop on your hamsterwheel from one tier of raiding to an other, worked only so well because you got fresh encounters. At some degree sets had sometimes cool set bonuses that changed the gameplay a bit but that isnt the point.
You wasnt farming the items because of the aspect of item farming but to explore new areas of the game and new lore aspects. Another aspect was to compete with other raiders on the server/in the world.
Such a “Gatekeeper” concept of gear for d3 is to my mind boring and is especially boring for d2 fans like me because we know the feeling of fresh and new Items and finding super Rare items. It is not fun achieving something when the game is basicly throwing everything at you. If you could going from highschool to bachelor to master to doctorate in 10 days, achieving P.D. wouldnt feel like a achievment at all. When everyone basicly gets everything without any effort at all it stops beeing an achievment. d3 was way to casual and boring in that department to my mind.
To be sucessfull as wow with that “wow-like” gear concept, d3 had to release complete new gameplay elemants and areas ~3 times a year to keep the game fresh ( like poe did). Blizzard didnt. So d3 become an Arpg without interesting item Progression and Itemcentric-Gameplay. To my mind the Gameplay and Progression via Items was plain and boring.
offtopic personal rant
Only positive aspect for me was/is that because of that super easy equiping of a character i can compete with other people/ teams for high gr rifts. but even under this aspect i am quite salty. I was Rank ~80-300 in some seasons and it was basicly impossible to be as a legit player in the top 50 without maphack aka turbo-hud and botting for paragon and gear. i even saw streamers and youtubers where the guy was saying “i am 100% legit”. But they were porting like magicans into an area where there was like a ~30% chance of an elite standing. Furthermore the always found the perfect path on the maps, where finding the path could be tricky. If this only happened ones, ok the person was lucky, if this happens 15 times in a rift than its 
especailly in a “4 hour push-stream”
3. Item Balance
Now i will show you some numbers. Pls dont nail me on them i dont found them out after 2 days of excel researches. So if some one have exact numbers you are welcome to share them. but i am pretty sure the numbers are ~ +30%-30% correct because i played both games a lot and because of that i can provide an appropriate guess.
In d2 the difference between a pretty weak character under the aspect of single target damage and a very strong character was like ( Depending on class and build because the classes even scaled differently with gear, for example barb had the strongest scaling with weapons because he used x2 2-hand weapons )
around 500-700% in offense and something like 200% in defense. so the differnce of a strong and a weak character was basicly by the factor of ~7 times stronger. you felt in a 8 man hell run basicly the same as if you was doing hell with a quite fresh bad equipt hell character solo. in the defense department you could survive something like instead of “2 mistakes” “4 mistakes” for some minions. for other minions you was onehit even in highend gear ( ww into iron maiden → haha ).
in d3 the difference is much bigger. When you have farmed appropriate, have appropriate lv gem and have like 4k paragon (highend in season). and compare it with a weak para 800 char ( non ancient all slots, i know its impossible with para 800 , gems lv 100) the differnce is like ~20 gr solo at least.
20 Gr Solo is 1,17´20 which is is like 2300% difference. And i am not even taking the set bonuses where you get like 40000% more damage and items which increase your skill damage by 800% into account. In yellow gear you farm i guess 80 gr lower, what is → 28.501.580,24 % less damage.
That is the reason why the itemesation is poor in d3. You have to find the items. No one want to do 28 million times less damage!! While a highend char can kill a boss in 10 seconds the 80 gr lower yellow guy would need for the same boss only 88,78 years!! Seems like a good itemisation for me
That is not how good game design works. people should play in the difficulty they want and like without sever disadvantage. when someone want to have an interesting rift which is ~3-4 gr under his max gr, he needs like 10-13 minutes for it. That is over 3 times slower than 8 gr lower!! A 8 gr lower than top gr is just plain and boring. That is not a good game design. If you force someone to “chose” doing basicly the same content it is bad game design period. It would be different if you chose another build which plays completly different. This feels at least entertaining. In a gear and paragon farming environment, playing the same build a lot “less effective” is not a choice, it is a mistake if your goal is achiving effective gameplay.
So someone who dont like easy gameplay and want be effective at the same time cant have that? It is possible in a lot of games why this shouldnt be possible in d3? because to your mind d3 is perfect in this department as it is ?
P.S. i Underestimated the wall of text by a lot
