It can also serve as proof of human. How many bots will back their accounts with bitcoin?
Discussion
As many as the developer wants. It is not like bots exists without their inventers. 🙂
As many as the developer can afford. There's a difference. You could argue that you just move funds from one bot to another when it becomes widely known and blocked as a bot, but then we have time. The longer the funds have lived at the pk, the more you trust it is a real nym and not an attempt to game accounts.
It's similar to what joinmarket uses for Sybil resistance.
A JayZ with 1Btc for 1 year is more reliable than one with 1 BTC for 1 week.