Many people who joined airdrops like blockchain.com giveaways has come from 3rd world countries in my opinion and this data that you said that might get stolen are not so useful and not interesting to stole you know what I mean? This are ordinary people trying to earn some small amount of crypto and educating themselves about blockchains if you are rich and has private data to protect will you join those airdrops for some bucks?
Sure, but their identities will have important role in their lives at some period later. Maybe years after the day they do their KYCs to receive airdrops, bounties. Sometimes, they feel they won't have other options to reject KYCs, but maybe later they will understand they are wrong.