In the old days, users used a platform only once and suddenly an airdrop was announced. That happened in the first one, the Uniswap airdrop.
Airdrops were here before the platform running Uniswap was launched. I can recall
ClamCoin made an airdrop to BTC, LTC, DOGE in 2014.
And the airdrops become more and more difficult, demanding thousands of crypto transacted, in a lot of transactions during many months.
This incentivizes a flood with meaningless transactions. Hopefully, privacy-enabled tokens and zero-knowledge finance will eliminate this disaster.