I support KYC for legitimacy check especially to claim bounty rewards or required by such exchanges but it's also bit a risky hence that's your identity that could also can be used by other people online if they have access to your submitted documents just like what happened to Binance kyc leaks incident. In order not to fall from this KYC process, it is best to filter airdrop and bounty campaigns that doesn't requires identity checks.
I agree with you, there are still many successful projects without Kyc, so why bother registering with projects that ask participants for Kyc.
although there are some who ask for kyc at the end of the campaign, I personally think it's better to classify the project than to fill in kyc which doesn't necessarily get the results worth it.