They do, although in my experience Google Maps is better at this. I actually find Apple Maps to be perfectly usable for everything, but always use Google Maps for directions to the boonies if I'm going hiking or something -- it's much better at caching tiles and keeping them around for directions back once I'm out there as well.
Yes offline maps is nice but the infuriating limitation is that it will save map tiles but not locations or areas that I've saved in "My Maps". One would expect a couple of coordinates to require much less storage than a bunch of map tiles...
