CRDT (or similar solutions like OT) is important if you ever want decent offline support and true real-time collaboration. Even a user with a spotty connection is essentially "occasionally offline". Having a single coordinator "in the Cloud" doesn't really solve the concurrency issues.
However you also want a single coordinator. It will give you the best performance. If you want to have people in a call to be able to move their cursors around and see each other within a second it will be very hard to do with sending everything through a database and polling or similar. But this can fundamentally be seen as an optimization. The client could just push writes and pull new changes to the database every couple of seconds. But this is both less efficient (the client needs to retain more history and do more complex merges) and higher latency.
CRDT (or similar solutions like OT) is important if you ever want decent offline support and true real-time collaboration. Even a user with a spotty connection is essentially "occasionally offline". Having a single coordinator "in the Cloud" doesn't really solve the concurrency issues.
However you also want a single coordinator. It will give you the best performance. If you want to have people in a call to be able to move their cursors around and see each other within a second it will be very hard to do with sending everything through a database and polling or similar. But this can fundamentally be seen as an optimization. The client could just push writes and pull new changes to the database every couple of seconds. But this is both less efficient (the client needs to retain more history and do more complex merges) and higher latency.