Migrating from Twitter and Facebook is much harder than migrating from Reddit. Twitter and Facebook have you follow mostly individuals, so if those individuals don’t all move at the same time to somewhere new, you never get the network effect. Whereas with Reddit, you follow topics. A list of topics can start small and grow with the community.

And you don’t need even .1% of the users of Reddit to make a good community. As a Reddit user of 16 years, I would argue that good communities actually only happen when they are smaller like what we have here now.