I am a bit late to share an answer for this one but I would still explain why most airdrops don't pay participants with the tokens being airdropped by the project owners. To tell you honestly, it is a complete waste of time if you want to participate or join in any airdrop. As I have said, airdrops not paying participants is one of the reason why the participants not getting paid which is very obvious. The second is that the owner is either very busy managing the project, very lazy, telling lies to people where they said they pay their participants when they join the airdrop. Third, I don't think that airdrop is still a trend until today unlike few years ago. Fourth, airdrops doesn't reward that much or you will only receive small amount of money minus the transaction fee and more fee.
^In addition, because it depends on the project itself if they have a failure, they will not get pushed through which means most of them will abandon if seeing they did not succeed which is all projects now don't have a real utility or it is repeated by other projects.
It could be the main reason is project failure, or once if they will succeed, they will pay only a small amount, because not all projects will have an amazing value after listing on the exchange, they will eventually encounter failure which if they don't survive that is the reason they don't have value.
So that is definitely right don't waste your time in airdrop hunting, it is worth nothing as of now.