The intended purpose of RCS was to be federated between carriers, just like SMS. If you centralise it then it's just a worse version of any of Google's abandoned chat apps. But there's a realpolitik reason to insist on centralised RCS: because it's already got the reputation of decentralisation, it makes it look like Google is better than it actually is.

> The intended purpose of RCS was to be federated between carriers, just like SMS.

Oof, so it was essentially destined to fail when the spec was being written.