So we have two mental models: (1) ubiquitous social media like YouTube is so large and important that it has become a public service, or (2) ubiquitous social media like YouTube is so large and dominant that it has become a monopoly.
The weird part about the "public service" argument is that it's hard to say I would ever want tax dollars funding "video distribution," while I don't have those qualms around distributing water and electricity. Content feels different to me. But maybe future generations will look back on that and laugh.
The weird part about the monopoly argument is that the barriers to entry for video hosting and distribution are low, and there are many different social media platforms, so the only thing YouTube has a monopoly on is... being YouTube. But perhaps that's enough?
Ultimately I'm more sympathetic to the anti-trust argument, that we should take action to break up mega platforms (although I'm not sure what that action should be).
What has more appeal to me personally is establishing a Constitutional Right to Privacy, then apply that right to ban surveillance capitalism. (US-centric framing, sorry; I would advocate all democracies adopt such a right.)
Such a right would mostly break up social media, with the side effect being an unknown degree of harm to online platforms in general since it's pretty hard to operate the server-client model without tracking your clients. But we could work around that, perhaps with local-first software, or by common-sense provisions like the idea that a store can keep a record of your purchases, it just can't share that record with others.
There's no obvious easy solution here, but this is a big society-shaking problem so I think there's no doubt we will take steps to solve it, the only question is which path will we choose, and how will it work out in the end?