The bot accounts are probably created by means other than Steemit's verified account creation process. Anyone can create any number of accounts directly on the blockchain if they pay STEEM for the transaction, as far as I understand it.

What I want to know is what whoever creates these bot accounts is getting out of it. As far as I know, you can't really profit directly just by following people, so why do they bother? I don't think there's a way to resolve the issue without understanding what the incentive is.