"RCS as a messaging platform just isn't that good. The end result of a 2008 standard with a bunch of extra features slapped onto it is still sub-par compared to platforms like iMessage, WhatsApp, Signal, or Telegram. Other than Google being desperate for one of the few messaging solutions it hasn't exhausted with mismanagement, there's no clear argument for why RCS is worth this effort. In the dreamworld utopia where Apple wants to work with Google and Samsung on a message standard, those three companies working together could do much better than a neglected carrier messaging standard."
https://arstechnica.com/gadgets/2022/08/new-google-site-begs-apple-for-mercy-in-messaging-war/