Then you get the other side of this problem, the echo chamber effect. If people self sort they'll eventually end up in social circles that are completely illegible from the realm of physical politics, which leads to a political instability of a different kind.

It's a hard problem. I think multi armed bandit based algorithms can help. Bluesky is a sort of "live" example of self filtering and it ends up creating a lot of fractional purity politics over which filter bubble is the just/moral filter bubble.