The answer to your question is more than obvious, since the new wallet cannot claim retro airdrop, buyers are trying in this way to eligebet for airdrop in the future. And it is transactions on the Ethereum network, as a rule, that will act as one of the conditions for receiving airdrop, since sibyls avoid interactions on this network due to high commissions.
I also think it's so somewhere along the lines, but don't think it has to do with high fees of ethereum or that sybils don't have resources to make transactions, rather I feel that projects who gonna do retro airdrop will outright disqualify wallets which are new for reason that it might have been created for farming airdrop, so sybils are trying to avoid that and are looking for older wallets.