My novice read of it is that Google made the mistake of trying to hand off the management burden to carriers, since they felt that the way to make something universal like SMS/MMS is to include carrier support.

But that obviously didn’t work because there are hundreds (thousands?) of cellular carriers around the world and they are the wrong people to manage such a thing.

So they basically are steering it back to “Google’s shitty iMessage.”

The universal thing isn’t the carrier anymore, the universal thing is the Internet that runs on top of it, which is perhaps why just about everyone outside the US tends to use messaging apps like WhatsApp/Signal/WeChat/etc.