You're talking past each other. OP was framing Twitter as a "natural monopoly":

https://en.wikipedia.org/wiki/Natural_monopoly

The barrier to creating a new social network once network effects have locked in a few major players is enormous.

In this situation, the market is more efficient when the large incumbents are granted a highly-regulated monopoly status.

That's how power companies work. You don't have new power grids cropping up, but the main providers are held to much stricter standards that a normal private company in terms of their quality of service and how much they can charge.

If we allow mass-scale social media to continue existing, we need these sorts of strict regulatory standards. These companies have become mad with power, and there's no way to unseat them through ordinary competition.