Nonsense. The standard is owned by the GSM Association that represents 750 mobile operators worldwide. How many companies have a say on the direction of travel for iMessage?
It isn’t owned by anyone. It was codified by the GSMA and anyone is free to deploy it in any manner they choose. Carriers did, and had their own closed systems that couldn’t talk to any other carrier. Samsung did and it couldn’t talk to any other system. Now Google has and it can’t talk to any other system. The API is CLOSED. There’s zero 3rd party access to the Google RCS network.
The only nonsense here is your post, which is comical in how poorly you understand RCS.