Which is odd, because I mirrored a site about a week ago with nested subdirectories, and it worked fine.
A few minutes of experimentation yielded the fact that while I couldn't copy directories into subdirectories, and couldn't create directories in subdirectories, I *could* just copy an entire directory - with subdirectories - recursively, and it wouldn't care.
Works fine, too.
Why are they trying to block that? I don't get it. It seems to work fine, so what's the deal?
Moral: It doesn't matter if your software is open-source or closed-source, it's still capable of containing idiotic decisions.