Filter Bubbles, Polarization, and Social Media Platform Speech Restrictions

One common response to objections about social media platforms' speech restrictions—whether on speech about people's gender identity, about the possibility of COVID leaking from a lab, and more—is: "Start your own platform." And I appreciate the merit of that argument; that is indeed how the free market usually deals with companies imposing restrictions on their services that some customers dislike. (We saw with the Parler story that sometimes Big Tech will try to leverage its power to block even those new platforms, but let's set that aside for now.)

But another common critique of modern American politics is that social media has helped push people into their own filter bubbles: People on the left tend to read overwhelmingly left-wing sources, people on the right tend to read overwhelmingly right-wing sources, and this tends to make people more and more polarized. Some element of that is of course inevitable, because it's just human nature. Even before the social media, liberals would naturally read one set of magazines, conservatives another, libertarians still others, and so on; those are the publications whose editorial judgments each of those reader sets trusted. Yet, the argument goes (and I appreciate its merit as well), many readers have gotten more and more insular over time, in part because of social media features and algorithms that reinforce that.

So here's my question: Say indeed that conservatives do manage to create viable alternative social media platforms where right-wing views won't being blocked (but perhaps left-wing views will be). Won't that just further increase polarization and filter-bubbling? At least on an ecumenical platform, people have some more chance that some of the people they're following will say something outside the bubble. But as people are pushed to Conswitter and Libwitter and AntivaxOKwitter and so on, they'll be seeing fewer and fewer things they disagree with, and getting in fewer and fewer possibly enlightening and broadening conversations with people they disagree with. Social media platform speech restrictions would thus just become greater fuel for The Big Sort, at least if the "start your own platform" advice is followed.

What do you think: Is that likely? Would that be on balance good or bad? Is it something we should think about in deciding whether to praise or condemn social media platforms' speech restrictions?