Defederating means not interacting with the crowd Meta brings in. I have a bunch of other reasons but that's my main one. And before you suggest blocking, you can't possibly expect me to block all 10M of their users and the domain block is bugged. I know because I tried.
Besides, this place doesn't look like much of a barren wasteland since we're interacting with a bunch of people right now. I don't mind interacting with only weirdo nerds if they're nicer people. Quantity doesn't mean quality after all.
For the people who want to interact with Threads because of family and friends, they should just make an account there. Just don't let Meta destroy this small part of the internet.