> I think we really need to interrogate this idea that filter bubbles are a bad thing. Some of the biggest negatives of twitter (and positive in terms of engagement) is that you have these groups that are opposed, and then a tweet from one bubble goes viral in another causing a war between bubbles.

"Thing from one bubble goes viral in another" doesn't require two bubbles to exist on the same platform, as in Twitter. If the two bubbles are segregated to different platforms, people will still post screenshots/etc of one on the other, and some of those will go viral. "Libs of TikTok" is a good example of this – TikTok and Twitter aren't federated, but that doesn't stop left-leaning TikToks becoming viral in right-leaning Twitter; and you can find plenty of stuff on TikTok critiquing "Libs of TikTok" (and Twitter more generally) in turn. Similarly, there are whole subreddits devoted to stoking outrage at screenshots of Twitter and Facebook posts.

No doubt a shared platform accelerates this mutual feedback process a bit, simply by reducing the friction of cross-bubble quotation; but it still is going to happen a lot even without one.