Seems dangerous if the rules are not adjusted right. It could end up amplifying certain narratives and extinguishing others, and causing a divide between sets of people as they move to communities where they don't get blocked. Furthermore an AI would be more opaque than a simple voting system, and could easily be manipulated for unethical purposes. Lastly, this sort of system would heavily bias towards the mainstream viewpoint, which is a good heuristic, but the mainstream isn't always right about everything. There is a place for minority voices. I would posit that the extreme political division we now see in the US is a result of more powerful systems for influencing online discourse.