It's not just a shitty place, as a corporation it actively fuels shitty practices that are felt across all social media and the internet in general. I'd rather take their users and build something better with them.

It doesn't feel great when you want to make the switch just to find the analogous lemmy communities have 100-5000 members with the last post being 3 weeks ago as opposed to 100k+ with 10 posts in the last hour. The only way to fix that is with new users. Whether from the old site or not, new users is how these communities will grow and flourish. If you want to gatekeep, go ahead but I think you'll only be slowing the adoption of the fediverse and letting the problems that incentivized its creation fester.