Messages is understandable since as far as I know Google is keeping tight control over RCS. It’s similar to why Signal abandoned SMS in my mind. Apple doesn’t allow 3rd party access to SMS and Google seems to be playing the same game with RCS (which requires doing the same to SMS). Supposedly this is meant to be temporary but with all the reliance on SMS for 2FA I dunno if Google may have decided it’s a security risk to allow 3rd party access. Dunno if dialer decisions cascade from there somehow.

Frankly I’m fine with it. SMS and RCS (and all carrier-controlled messaging) should be considered obsolete and privacy risks.