Some people usually cheat to get referral. And developer don't like it because they don't get anything, they still lose money.
Hmm, actually I think that it is even easier to cheat in bounties that require you to register with Google forms only, then in those where you need to register on the website of the projects, as in this case the team will be able to check IP-addresses and thus ban all accounts using the same IP. But in the current model it's only Google account used to fill in a form that is seen to a manager, so easy to cheat.