How can passing KYC help to fight cheaters? There are tons of passports, id and drivers licenses available for free in the Internet. With little photoshop skills you can edit someone else document and make it look like original. MS Paint can even do that. Just select letters from the picture and copy/paste them in right order and voila, document has your name and surname.

Bounty managers and projects does not created "bounty hunter-his ID" database. For example I can participate in one campaign as George Bush, and in other as Vladimir Putin. No one knows who is really behind account or monitor.

KYC does not prevent cheating, it just scares lazy cheaters from participating.