Don't think it was federated at first if that's what you're asking.
It you're asking why users didn't migrate, probably because we like a forum experience rather than microblog following. I tried out bsky and it was a lot of pups. Like a lot. Like a pup fucking a pumpkin came up front page. I wouldn't usually care, but it wasn't marked suggestive.
Anyway, probably because there's no pups on threads.
I found there was too much cat stuff on threadiverse at first. I enjoy a cat in a box or a cat on a keyboard or "this is my life now" or even wearing a kitten as a hat here or there but the whole things was cats cats cats with arch linux memes mixed in.