Right, the idea that OT requires a "central server" is a bit of an oversimplification. It requires an authority that can serialize concurrent revisions into a globally consistent sequence. By far the easiest way to achieve that is an actual central server, but distributed algorithms have also been published for a long time, for example SOCT2 which uses a state vector.
The downside is the complexity. Now there are more things that can go wrong: the OT algorithm can fail (either due to bugs or because of corrupted data), and now also the distributed consensus algorithm can fail as well. When you have this level of complexity, going to CRDT is pretty appealing as an alternative.
The downside is the complexity. Now there are more things that can go wrong: the OT algorithm can fail (either due to bugs or because of corrupted data), and now also the distributed consensus algorithm can fail as well. When you have this level of complexity, going to CRDT is pretty appealing as an alternative.