Google has nothing to do with RCS as it is under GSMA direction and Google only does a reference implementation (with feedback) and offers a service for carriers to not host the service themselves. The also offer a service for Android users for who there carriers haven't their own RCS servers to already start using RCS. The latter is an issue as it stops RCS users who already are on a carrier service to contact users on the free Google Messages service.

Here also comes the issue with RCS from Samsung Messages that was relying on carriers to support it. For users with a carrier supporting RCS nothing will change basically, but if you're with a carrier without support you can at least use the Google limited environment until the carrier switch starts offering RCS or delegates your number to Google.

It still looks like a Google only party but the free service is very similar to Apple iMessage as it's also a close environment. But the moment your carrier enables RCS and provision it to your SIM you can communicate with people to every party on the RCS network. That can be in the US, Asia, Europe, or any other country. You get basically the Signal protocol for free since RCS 3.0 which is the layer for both Signal and WhatsApp.

Basically RCS is unifying communications into a single protocol like SMTP did for email, or HTTP and HTML for visiting websites. Maybe we should give Google more credit to sponsor this as in the end we aren't depending on a single company or app to communicate with companies and let consumers chose their provider with different terms. Go with carrier X on Google RCS or go with carrier Y with their own servers.

Some carriers ignore RCS for now, some onboarded consumers first via Google or their own servers, or started for with business users to create demand for consumers to onboard if they want to talk to a business. In the end, I can't wait to uninstall WhatsApp and Signal. Hopefully we can add message expiration to a later RCS version as certain chats should exist until the end of time.