It can be if your data structure is a simple tree. But usually it's a complicated, maybe inconsistent, multi-rooted graph. It got that way because of incremental implementation. As the article illustrated, you then have to tease out the pieces.

I once inherited a large enterprise system that had been designed from the ground up to allow that kind of flexibility. The problem was that there were so many levels of abstraction and indirection in the database and the ORM model that performance was abysmal.