I like this policy as I think it also encourages people to post to already active communities. Instead of a bunch of communities being created then a few surviving, I would rather see larger communities develop, then smaller communities break out from them as interest in more nuanced topics reach a critical mass.

My understanding is that some users dislike reddit but very much like their specific small communities in it. They want to maintain the value of their community without relying on Reddit to host the content, so they are trying to migrate to places like the Fediverse. With that being said, I only support that for smaller subs with their own established community culture. Also, transition is hard so some people want a few familiar landmarks while navigating this new land.