Is the take-home message of the post that the full complexity of CRDTs/OT is necessary only in the absence of a central server?
As others in the comments argue, this is technically a CRDT (though a fully general one); also, undoing/replaying ops is itself non-trivial to implement. However, I hope this is still simpler than using a traditional CRDT/OT for each data type.
Whether the converged result is at all reasonable is a different question.
That's the whole point of CRDTs: multiple replicas of the same data structure are managed throughout many nodes, each replica is updated independently, and they all eventually converge.
In my experience if you are persisting your edits or document state, you have something that creates an ordering anyways. That thing is commonly an OLTP database. OLTPs are optimized for this kind of write-heavy workload and there's a lot of existing work on how to optimize them further.
But now even S3 has PUT-IF, so you could use that to create an ordering. https://docs.aws.amazon.com/AmazonS3/latest/userguide/condit...