Many people use it. Regular android users have it enabled in their "Messages" app. But most rooted devices likely does not use RCS.

I guess it's similar to how people use iMessage because it's the pre-installed messaging app. Both fall back to of SMS/MMS if the other party isn't using the same closed ecosystem. I.e. Google's proprietary end-to-end encryption or iMessage.

I use it. I enabled RCS as the primary protocol since too many time critical SMS messages got too delayed.

Just as a matter of curiosity, how do you get rid of RCS specifically?