If someone is going to put that much effort into to it, let them. I think the ideas here are to try to get some low hanging fruit to see if that works “good enough”. You’ll never block all AI generated accounts, but you may not have to and still have the desired effect.

But if someone wants to plant 20 new accounts, grow them out with karma votes, so that they can game the voting, there are probably other ways to detect that.

Any amount of friction reduces the amount of slop. What proportion of clankers are going to realize that they need to warm up the accounts two weeks in advance? Answer: a proportion that your never going to see with that barrier in place.

With a couple few layers of defense, you'll weed out almost all of the bad actors. Without strong monetary incentives for spamming, you also avoid most persistent actors.