So, I don't think that this optimization is new (fast path for commutative operations), but it's very difficult to get correct AFAICT, because in order to garner full optimizations, you must know about the invariants being preserved. For example, adds can always be non-conflicting for a bank account, if say, the invariant is that a bank account balance must never go below 0, but withdrawals need global consensus.

The earliest knowledge I have of this is Generalized Paxos, but I believe there's more recent work with the likes of Egalatarian Paxos. I think there were even some CRDTs that mixed strong consistency and weak consistency.