And don't get me started once you have some hierarchies. Sometimes a object changes and you need to notify a parent of this change. OOP really sucks at this.
It seems like in these cases often at least in frame-based systems like games it makes sense to sort your data in a parent->child partial order, then visit in that (or reverse depending on which algo) order propagating changes, then do another pass later and so on. It's just nice that you can think about these things once you're in DoD-land.
