I'm still wondering why developers will organize airdrops and distribute an amount of tokens which is far lesser than the minimum amount of the tokens that can be deposited on an exchange for trading. If you don't want the users to cash out the money, why do you let them waste their time?
I think the main purpose of airdrops is publicity. Its like a free taste in a supermarket wherein you will decide to buy the product if it taste good. Just like in crypto, they will use airdrops and when you think the coin has a potential, you will be attracted to buy more during their presale. Its all about marketing strategy.