Need proof? - check diablo.trade. Lots of BIS 4GA meta gears with perfect aspects being sold by someone with random lettered name. Click on their profile to see which other items they’re selling and lo and behold a full set perfect gear.
So which one is it?
-They are aware but they dont care.
-They are aware but dont know how to fix it (very likely since this has been going on since season 0)
-They’re not aware (really?!)
Here’s another proof: imgur : HmNh9kx.png
Both first and second answers, they are probably not able to fix their game and they don’t care either
People still buying platinum so it’s fine
It doesnt matter there will always be some form of exploit from the gold farming industry.
Its just one of those things that comes with open trade. Its rampant in games with high playerbases because theres a lot of money to be made. I guess the only silver lining is it can control the “economy” to be friendly towards casuals who want to engage in trade. 
And here I am playing non-trade (self imposed) like a pleb.
The gold farmers use stolen credit card info to buy mass keys to get around any bans Blizzard could hand out. There’s not a whole lot they can do about them but diablo trade needs to be taken down completely. It’s a grey market reseller that engages in fraud. No different that CDKeys or whatever.
you dont even need those anymore. this game is practically free with gamepass.
Fix is simple - people wouldn’t be buying the gear if it actually dropped - or at least less people would - and if we could get it legitimately it wouldn’t matter either way as much. Blizz is enabling this with it’s appalling drop rates.
Duping was going on a couple days into season. They never addressed it. Never made news about it. Several forum posts warning about it taken down. They never took down trade. ITs still going on now. Never before in D4 history have they so completly surrendered to exploiters. Not only the ones duping items but also getting 18 resolve on items by exploiting tempers. Bliz is in white flag mode. 
What a shame. This is the best we can do is surrender to the bad actors? What happened to enforcing a fair game? Go back to D3 trade method if u have no idea how to prevent dupes.
This season is going to be known as Season of Dupes for now on. That is how bad it was and still is.
To answer your question this is the one to pick:
-They are aware but dont know how to fix it (very likely since this has been going on since season 0)
and then you’ll have some people on the forums tell you that the game is fine and you need to trade. Ya, no. Im not taking part in 3rd party trading. Especially now when its mostly dupes and they want cash or crypto because gold is worthless.
well, I’m still hopeful and it looks like they’ll be forced to actually do something. someone releases a vid in YT that actually shows the process of how its done. the vid is 3 days old with 9.3K views. I’m sure that will eventually spread and devs will be forced to do something.
You forgot one:
They are benefitting from it.
Open trade should have never been enabled in the first place. ALL of what we are seeing was very predictable. A child could have seen it coming. There is a real easy fix but it is being ignored.
These vids were out a month ago. Bliz has done seemingly nothing since I see no change in the amount of dupes going on.
Actually they are using it as excuse not to give us QoL changes like increased stack sizes - which is typical of blizz - they could put the work in to fix it, or allow it to go on and use it as a reason not to do other stuff! Calling this a live service game is a joke at this point.
I dont trade/buy stuff. I use what i find.
Sorry im an old person. Maybe modern times and people differ. 
And what about you know…fix dupping maybe? Instead of disable trading.
How can this be friendly to casuals if the item they bought goes poof because it’s a dupe…?
S7: Season of the Duping Reborn.
S8: Season of the RMT.
S9: Season of Trading Disabled.
Expansion 2: The Great Duper vs. RMT Civil War.
Dude i bought PERFECT GEAR on 2 characters this season and i have never been scam…PPL like you are just jealous one who cant afford to pay the gold price for get that gear…
I saw pictures of 6GA equipment circulating on the internet, and the game has been hacked?
This will broke trading price.
xD