I think this is a good example of why "simple CRUD systems" are actually much more complex than people usually give them credit for. Anything seems easy if you do it badly. But multiple people editing a document at once with CRDTs and undo is still even easier than a basic CRUD application done properly: now you have multiple people editing multiple different data types at once! In such cases we should be thinking about building CRDTs over all the various operations users may be doing with the data, which means thinking about associativity and commutativity of generic data operations. Git only has to deal with merging text files line by line; CRUD applications have to deal with merging lots of different data types!