Did Microsoft stores have “Geniuses”?
Good question. I've never lived anywhere that was close enough to one of the MS stores to make it worth the long travel, so I can't speak from personal experience. And to be honest, the same is nearly true of the Apple Stores, although I did visit one during a rare "Big City" adventure many years ago.
Surely MS had customer service personnel available in their stores. Whether they were geniuses, either in the Apple sense, or the dictionary sense, is not known to me.