First, baiting is still legal in well over half the state. Probably 3/4 geographically.
Hundreds of deer, over bait piles, you must be kidding. You were probably looking at an agricultural site.
Unine and defication, sounds gross, but the speculation is that it's passed by nose contact, perhaps dripped mucus, but it's only speculation. From imported deer I'll note.
It was a great panic 6 or 7 years ago, which the DNR lightened up on when it saw what it did to license sales. But not that big a deal, and I seriously doubt baiting played any role. Else it wouldn't be legal.
I used to hunt with folks in WI. They would guarantee hunts. They would put up massive ladder/pedastal stands and then begin bringing in truck loads of corn and pile it up a couple of feet high and 50 feet in diameter.....
The deer would congregate on these food piles for weeks before the season began. Hundreds. You can’t mill around in large numbers like that and not have an infected herd.
MN hasn’t allowed that sort of behaviour for many years, and we don’t have that problem.
I’ve seen it in WI. It did happen.