It is that isolated bubbles generate environments spreading and reinforcing dangerous information. E.g. spreading alternative medicine cancer "cures" will kill people. I believe everyone needs to be exposed to different views once in a while.
In theory I agree with you. Or I would have, had I never been exposed to Twitter.
Reddit has subs. Facebook is highly filtered by design. As far as I can tell Twitter is about as far away from a filter bubble as centralized social media currently gets but it's still full of hateful garbage.
At this point I think it's safe to say that the commonly perceived problems with social media can't be attributed to any single factor. Twitter stands as a counterexample to filter bubbles. Facebook stands as a counterexample to anonymity (real names don't seem to deter shitposting). Etc.
I'd also note that an increasing number of the people I know in real life are gravitating heavily towards group chats with family and friends. That's the ultimate filter bubble, but it's also much closer to how the typical person existed prior to the rise of the internet and smartphones.
