Coupled with the fact that testnet demands a high level of professionalism in crypto to carry out. Not everyone can run a testnet mining.
That's true. Testnets have difficult terrains to meander through as they're unfinished projects going through a period of test run. That's why devs and their teams ask people to run checks on projects for them. That's why not too many people are keen on doing them. Projects want to know what isn't working well or what things aren't in their right positions before going to mainnet. It's the reason why testnets aren't that easy to engage. Nevertheless, we've to acknowledge that rewards are better with testnets than with telegram bot airdrops because only a few people like running testnets.
I can remember telling my friends that Hamster may end up being one of the most successful projects in Airdrop era because they never requested anything from the community but paid the much they could.
Hamster also ended up as dust. A lot of them have been ending that way, disappointedly. Apart from Notcoin and Dogs that gave us something promising, maybe Not Pixel which will list this month will also do well, other ones are flop. Despite asking for payment to run tasks, they end up dashing airdrop hunters' hope.
I believe that Airdrop farming may tactically crash completely but it all depends on this January listings.
I'm gradually moving to testnets myself, and I believe many other hunters are doing so too.