Yes that's also my thoughts, I have all the code of my current employer on my laptop, what would you do with that code if you got your hands into it? Nothing really, there's not a single use case I can think of which could be useful to somebody.
Other than that I can't really think of use cases either for the code bases I've worked on.
Yes that's about it really, there's so much custom code related to our business that even if you are a direct competitor you are not going to get anything out of it.