In as much as I do not participate in airdrops, but I do bounty and I think KYC is very good because it helps to reduce the rate of scam in the campaign and also rude of fraud by registering with double account in the campaign.
Scammers always have solution and I am sure they can use someone else kyc details for bounties . and it is not the reason for asking KYC by Bounty Managers . Bounty Managers have to follow guidelines of project and if project need it he ask it . KYC is mainly used for investors so that no bad element can invest in that project . but few projects ask KYC even for bounty and airdrops .