Interesting. Maybe a bug in that culling system would explain why drops were so low. Because everything else I see doesn't explain to me, why the drop rates felt so different, and I mean in comparison to most leagues I played recently (I didn't do Archnemesis). If that is the case, they didn't fix the bug, but tried to fix the symptoms with the recent drop rate buffs. Which means this will probably have some sort of relapse down the line.
The drops are so "low" because people got used to juicing the fuck out of everything so that white mobs would drop stuff along with 10 or 100s of rares/uniques in parties. Something which no normal player did aside from slight juicing.
Now instead they moved most of important loot to rares and unique enemies and they lowered their spawn rate by factor of 2/3. Moreover amount of mods on those exponentially increases amount of loot generated and since they are harder you get Fight tough fight get a lot of loot mechanic instead of fight hordes of trash monsters get a lot of loot.
So juicing is a lot worse than just playing game normally and juicing stuff a little. AS the amount of rarity/quantity from juicing pales in comparison to mods stacking you normally get from playing high tier content.
Also personal item rarity and quantity got much more important.
Much needed change in POE for a looong fucking while.
I wish though archnemesis mods were better because they do indeed suck. Instead of creating some creative mods like on some of them like that one creating icewalls instead they went just with mostly numbers and statuses which is gay. Moreover magic monsters also have them so rare monsters aren't really that rare.