I don’t think it’s possible to mandatorily restrict editorialising without killing platforms. Any such restrictions would be a spammers, griefers and pornographers manifesto. Restricting editorial rights is a horrible can or worms to open.

But anyway, there are no social media monopolies. We have Twitter, Facebook, YouTube, Instagram, WhatsApp, iMessage, Discord, Signal, etc, etc, and it goes on and on. They’re also very segmented, Facebook is huge but it’s almost irrelevant to kids and young adults. New services pop up regularly because barriers to entry are incredibly low and segmentation is so high.