The long fight to make Apple's iMessage compatible with all devices has raged with little to show for it. But Google (de facto leader of the charge) and other mobile operators are now leveraging the European Union's Digital Market Act (DMA), according to the Financial Times. The law, which goes into effect in 2024, requires that "gatekeepers" not favor their own systems or limit third parties from interoperating within them. Gatekeepers are any company that meets specific financial and usage qualifications, including Google's parent company Alphabet, Apple, Samsung and others.
RCS is too little, too late. Its encryption is problematic, and people currently using it can tell you how inconsistent it is. It's what you get when industry players want to control things.
Why build RCS when everyone could use an existing, extensible protocol like XMPP? Yes, XMPP isn't perfect, but had the RCS consortium started there, then agreed to support specific features, we'd have a much better solution today.
iMessage works.