Sure for digital only ones, but machines that actually have physical spinning reels with the pictures on, how would that work? The dump will have all the actual code to control all the lights and and the logic for bonus rounds and holds and such, but as the actual reels are physical what would it spin when you press the button? There is a emulator out there that will play some specific games called MFME, but that requires nearly full reproduction of all the visual aspects of the machine in order to work they wont work in MAME "as is". I mean "technically" they would be "mechanical" games as they use specific hardware in them.
From the thread linked below,
"But MAME only emulates the roms, it doesn't re-create the image of the slot. MFME emulates the roms, but is also an editor that allows the creators to re-produce the appearance of the slot - normally from a scanned flyer."