> I contend that social media platforms of YouTube/Twitter/Facebook are at that level now. Competition is not possible and harm has clearly been done.

I agree with you, and I think the regulation we need includes data portability regulation: Make it a legal requirement for companies to allow you to get all of your data (which those companies primarily exist to monetize anyway) out of their web services complete, in a simple fashion, in a way which allows you to put it into your own system or upload it into a competitor's system.

Other laws might be required as well, but data portability would be a good start.