Indeed, I think Matrix state resolution has some CRDT-like properties. Afaik, the goal of this is mainly to manage room state across servers when using federation - but I'd have to dive deeper into this.
However, not all CRDTs are the same (actually, I think the definition is still somewhat vague - most things "eventually consistent" could be called a CRDT). Yjs is specifically designed for high-performance operations and has great support for rich-text collaboration. It also works great while offline - and you can connect different providers as you like (for example, store updates both locally in IndexedDB, and transmit messages over websocket / webrtc / and now, also Matrix). Definitely wanted to keep this flexibility.
However, not all CRDTs are the same (actually, I think the definition is still somewhat vague - most things "eventually consistent" could be called a CRDT). Yjs is specifically designed for high-performance operations and has great support for rich-text collaboration. It also works great while offline - and you can connect different providers as you like (for example, store updates both locally in IndexedDB, and transmit messages over websocket / webrtc / and now, also Matrix). Definitely wanted to keep this flexibility.