Right, but if you just accept that the communities will be ruined and just shift to the next quality subreddit for a given topic once people have started migrating it might be better for everyone. Making communities more ephemeral and giving moderators less power would certainly chap some asses though.

I know the site can't scale without moderators but I think giving them so much ownership has resulted in a lot of problems. I'm not sure how else to incentivize them but the amount of power they're given clearly is good at attracting the type of people that it shouldn't (as well as the type of people it should, to be fair).

You're also insinuating that any subreddit that hits critical mass becomes low quality.

That seems to be pretty much the case, there might be a handful of strictly moderated exceptions.