The idea is “how can we make the individual communities more like the interesting and vibrant communities that exist there”. There is no one single “reddit” to begin with. The main thing that made Reddit so appealing in the first place is that the people could make of it whatever they wanted, by choosing what subreddits to subscribe and participate.

Reddit’s problem is in its centralized control over this long tail of communities. Just that. If the subreddits could be left alone to their own management, no one would be talking about “leaving reddit” but would just talk about smaller issues on the subreddits.