This is likely a good conversation for another day, but one thing that increases the probability of us remembering UM blowing leads is that they have held a lead in a lot of postseason games for a lot of years. How many postseason games has a program like Union even played during a similar number of seasons?
It does happen to other teams as well. I remember your favorite program yielding a third-period lead during the season when it likely had its best chance at an NCAA Championship. Historically, they have been one of the best programs at executing when games have been close late, but not on that day. Granted, the Gophers have managed to do so with alarming regularity of late, particularly versus tOSU.
Both of those were atypical. Normally, there has been a cascading effect of defensive breakdowns, either on the play that produced the goal or as a pattern leading up to it. This time, those were pucks thrown at the net from angles ranging from bad to can't-see-the-goalmouth that found their way into the net. All one can do is to try to rally in OT, and that's easier to do if you're the better team. Clarkson and Wisconsin are both in the set of teams that Minnesota can defeat when things go well, but I wouldn't put either in a list of teams that the Gophers should beat.
Even great Minnesota teams have given up leads late (2005 versus UW in WCHA final and Harvard in NCAA Final; 2013 versus BC in NCAA semi). How a team responds shows whether or not they're really championship caliber as much as whether they hold the lead in the first place.