But it's still tied to your carrier. I'd really prefer to keep my communication disconnected from my connectivity provider. These should be two completely separate services that I can manage independently. I just want my mobile provider to provide internet. Full stop. Nothing else. But of course they want to inject themselves into as much of my life as possible to make themselves stickier with a nice side of siphoning up more data.

Imagine a world where your ISP also separately provided an IRC messaging service. Why would you ever use that over actual IRC?

This is how I feel about SMS, and phone numbers too for that matter. They're still around for historical reasons, but if we started anew, I can't imagine we would build out that infrastructure separately from the greater internet, and if we would have, I can't think of a reason why.