The fediverse gets all those centralization advantages without being centralized. However there are not (yet!) the quantity of people needed to make it work.
Depends on what you want. some places you can find just as high quality. There is a lot of junk out there to wage through. They also have a "allergic reaction" to the thought of an algorithm to curate feeds which throws the good out with the bad.
I would very sincerely ask what places and what quality?
More like which niche. I find transit advocates do a lot on mastodon. There are also a lot of great open source projects (the curl maintainer posts some interesting stuff). Those are niches I'm interested in though, YMMV in anything else.