IIRC their point was that SMS is insecure, so they don’t want people using SMS in Signal to think that this is Signal. With RCS, they could do what Apple will - be interoperable while providing extras with own platform (iMessage).
Admittedly, that doesn’t sound like enough reason to reimplement SMS and RCS alone would still be kind of inconvenient.
IIRC their point was that SMS is insecure, so they don’t want people using SMS in Signal to think that this is Signal. With RCS, they could do what Apple will - be interoperable while providing extras with own platform (iMessage).
Admittedly, that doesn’t sound like enough reason to reimplement SMS and RCS alone would still be kind of inconvenient.
they could go the apple route and just make sms messages an ugly color