From bitcointalk account, to facebook, twitter, telegram, and Discord. I don't think that all bounty cheaters already have all set of accounts on those channels for each of their bitcointalk account in order to cheat bounties. So, if they use same accounts (such as Telegram, or Twitter) they will be discovered (by bounty managers or by forum community). Then, at the end, they all will be found, and punished (with nuked or red tags). KYC requirements for bounties are unneccessary, in my opinion.
Not all bounty managers are keen on finding cheaters and abusers, Sometimes they only rely on the community effort in exposing the cheaters and sometimes bounty managers themselves own hundreds of farm accounts that he will use to abuse the campaign the they manage.
This is our big problem here in crypto they should required KYC only in ICO project owners to avoid from being scam.