I think you neglect the reduction in votes as an incentive to self vote. HF 19 reduced the number of votes that can be cast by minnows by 400%. During the time HF19 was being discussed and developed, the number of posts rose by 1000%.

The number of votes available to be cast has been reduced dramatically, and those new to the platform are starved for votes.

I don't think the exponential weighting extant prior to HF19 reduced reward pool mining at all. Virtually all author rewards went to a handful of accounts, and as far as I know that hasn't changed at all since HF19.