People that follow college football know that it is common for lower division teams to play pre-season type games with upper division teams. It happens across the board, all divisions. Wins can occur if the challenger fields a really good team and the upper division is mediocre or bad. There's nothing unusual about this. Montana had a really good team and Washington a mediocre teams. It happens.
Ok, first of all, it's a little pedantic to say "people [who] follow college football know …." on this forum. Just think about it for a minute.
And your fetish for subdivision football notwithstanding, those losses are so rare that people still talk about them decades after they happened. People still give Michigan shit for losing to App State in 2007.
The talent across the board at Wisconsin is on another level from that at Montana. The offensive lines are not even a conversation.
Look at their schedule and results and tell me what it would look like if Montana were subbed in. Come on. We talk about grease around here for a reason.