But this “2e12” algorithm will have practically zero effect on bid bots

To address this specific point, the convergent linear curve has literally nothing to do with bid bots. Its intent is to address profitable low level reward milking using enormous numbers of comments spread widely where they are hard to find. This is much harder to deal with using downvotes, since even with the free downvotes in the proposal, downvoting is still unrewarded so relies on altruism and voluntary effort. Bidbots are pretty much the opposite, as their function is to push posts to the higher end of the payout distribution.

I think $6 (if that is indeed the right number, I've seen conflicting claims) is probably more than enough for this.