And I forgot the worst part which is that most of these workflows assume that A() will return the same answer for the duration of the interaction and that’s just not true. Passing value objects on the stack guarantees snapshotting. For the duration of the call sequence, all of the code will see the same A. Not so with the cache.

You make still run into problems where you expect A and B to have a relationship between them that doesn’t hold if there’s a gap between looking them up, but it’s often less likely or severe than if for instance half a page has the data in state S and half of it is in state T.