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.
As someone i do not remember said: "what the first did was smart, but is not smarter to repeat currently". And the airdrops become more and more difficult, demanding thousands of crypto transacted, in a lot of transactions during many months. One example was Paraswap, who exclude many users from their airdrop and caused widespread anger.
Coming back to the old days, hunting airdrops was basically to follow few insiders, read the news and use all protocols that had no token. Currently there are thousands of influencers announcing airdrops even from projects that did not comment, projects announcing airdrops before have a product and a lot of noise.
I feel is is getting harder and harder to get good airdrops, when some arrive the tokens are diluted by a huge amount of airdrop hunters not to mention projects that "gamefi" airdrops with tasks and points, terrible.
Maybe it is a wave that passed, not sure about the future of airdrop hunting.
The airdrop criteria are getting more difficult because we are being greedy. They had to take some initiative to get rid of the airdrop farmers. I think all of the projects want to send the rewards to their community equally or based on their level of participation. But some people try to go around the system, so all the projects are trying different measures to overcome these challenges. Legit and loyal users are also affected because of this but if you want some free money you still need to do some contributions for that project. I think this requirements being hard justify this because you are only investing your time in here.