I have been following this thread but never responded, so here is my take.
Too much rng, well to this question I will refer to D2 as well.
In D2 the high runes, anything higher than Mal and Ist, was a nightmare.
There was a lot of rng in that game as well, you could find BiS weapons and other rares but those were extremely rare. No pun intended!
That made the grind interesting because it meant that there was always room for an upgrade.
An example from my time in D2 20 years ago, times flies by ;), was a rare axe that had do much damage on it paired with very high elemental damage that it would have been godly. It was ethereal though, so I never got to use it because good luck getting a Zod.
So here we can draw the following out of this little story.
Items that can be generated godly is something we can have the patience to wait for, items that can be useful in so many ways like the high runes should not be so incredibly rare. On the other hand they shouldn’t drop from the sky either. I think you understand what I mean.
In D3 we have an easy, relatively, way to get our desired items the hard part is to gather perfect rolls for them. In this regard d3 has a better rng, the primals and getting them perfect is the next nightmare of course. Keep in mind that this is said in general there are specific items that can be near impossible to get perfect or near perfect even.
In conclusion I think that the drop rates can be high but not near impossible in most cases.
Thanks all for your views always good to see different opinions.