Samsung is not done with Samsung Messages it is a carrier enabled feature and a lot of carriers like AT&T and TMobile for instance only allow RCS Messaging via Google Messages this is why they first started making Google Messages default and then not Pre-Installling on devices because people are confused by having 2 Messages Apps and then not being able to use RCS Messaging I myself have …
https://us.community.samsung.com/t5/Galaxy-S-Phones/RCS-for-Samsung-Messages/td-p/3024239

