There are exceptions though, where the domain model is trivial, but you will be mystified without the sequence diagrams. Paxos for example has a trivial domain

There are exceptions though, where the domain model is trivial, but you will be mystified without the sequence diagrams. Paxos for example has a trivial domain model (a value that's supposed to be kept identical on all nodes in a distributed system) but the consensus algorithm is non-trivial enough that a lot of people claim you should not even try to implement it (and opt for Raft)