>Imagine, for example, storing a unique count in the database. There's no way to know how to combine divergent values in that case. (If the root value is 4, and you have two divergent values of 5, you have no idea if the increment was due to the same element or not. The right answer is either 5 or 6, but you have no idea).

if 2 nodes are allowed to accept writes for the same "cell" independently without synchronization, ie. node A : 4->5, node B : 4->5->6 how your schema would work in this case? (of course any schema would work fine if only one node allowed to master the "cell" )