The hyper-polarization is probably preventable, in my estimation. The main thing a social network would need to do is to stymy the flywheel effect that allows a handful of users (and thus sets of norms) to come to dominate so strongly. That might mean something along the lines of a system that puts a hard cap on the reach any profile or topic can have, and when engagement exceeds the triggering threshold, reach actually tapers off proportionate to how far the threshold is exceeded.

In theory this would naturally elevate posts that are more measured and mundane while sinking posts with big emotional lizard brain appeal (by design or otherwise). With time this would establish a self-reinforcing norm that makes polarized and inflammatory posts look as clownish as they actually are.