Except ATT and telecoms require specialized infrastructure with federal and local government cooperation. The infrastructure was/is largely subsidized and laws requiring public cooperation (right of ways etc).
Social media and streaming content companies aren’t this. If they buy up all the data centers and telecoms to start censoring what they will host, I’d be more sympathetic toward the cause of breaking them up.
Facebook, and Twitter, use that same infrastructure that requires public cooperation, additionally they get special protections, like common carriers, as opposed to being treated like a publisher. Does AT&T monitor your calls and shut them down if they think you aren’t telling the truth? and that is part of why they get protections publishers don’t. I would be fine with Facebook and Twitter censoring whatever they want and allowing those things they like to be published, if they had the same protections as publishers (none). If they stuck to trying to remove copyright infringements and porn then that would be ok, but they have gone way beyond that.
However just because Google, Facebook and Twitter are successful doesn’t mean there is an unfair barrier to competition. Anyone including you can make a competitor tomorrow. There isn’t some unfair anticompetitive practices stopping you from making the next social media platform.
Alex Jones is banned from these platforms he found somewhere else to spew his views. That proves there isn’t a monopoly.