The massive sell is expected because many airdrop participants are not investors; they participate to earn income. This is essentially the price they pay for free promotion of their projects, which is considered a form of compensation.
If the project is that good, it can withstand the sell pressure and can maintain its presence in the market. Airdrops cannot kill good projects; it’s the utility.
That's why some projects raised eligibility requirements. To prevent airdrop hunters from cashing out and causing a huge "dump" in market prices. Now you're required to spend a certain amount of money in "De-Fi" protocols to be able to participate in the airdrop program. Other projects expect you to follow them on social networks and invite other people to their platforms.
Gone are the days where you could claim "free tokens" out of nothing. Back then, we could say airdrops "killed" the value of new projects. But things have changed as developers noticed airdrop hunters' schemes. I think this is good because it encourages utility above all else. Mainstream adoption will increase as people rush to meet eligibility requirements to receive "free money". The success of airdrops will depend on the regulators. As long as regulators don't mess this up, there should be nothing to worry about.