[fuwafuwa]

I believe OO is good for exactly two things: abstract data containers and state machines.

In the former, access hiding cleans up the API and prevents unsafe usages of the container. In the latter, OO enforces a protocol to keep the state machine sealed off and only aware of key inputs and outputs.

And that's it. I've found nothing else. Data itself is better off when strategized to fit in a database, whether off-the-shelf or a custom-tuned, in-memory design. The state machines may need to query a part or all of the database, as well, so their ability to restrict scope only goes so far.