Blake and Breck ARE high school teams! As are other private schools, like Hill-Murray, Benilde-St. Margaret's and St. Paul United. Blake, winner of four of the last five Class A State Championships, has decided to "opt up" to Class AA beginning next season. There, the road to another State Championship will be much tougher as they will be facing teams like Edina, a public school that is sending 8 of their graduating seniors to play D1 next fall. In Class AA it's the larger suburban public high schools that have ruled the roost for a long time; in fact they have claimed 8 of the past 10 titles: Minnetonka (3), Eden Prairie (2), and Edina, Roseville and Stillwater one each. The lone private "hockey factory" to win it was Hill-Murray who won it twice, in 2014 and 2015. And in 8 of the past 10 years the runner-up in the Class AA final was a public school (Hill-Murray and Benilde-St. Margaret's being the only exceptions). Arguably I suppose you could call all these schools "hockey factories" because they're good at it with a large number of their players going on to play D1 and many more at D3.
That would take a dramatic turn-around from the status quo. I don't see the number of Minnesotans on D1 rosters going up from what it's been, but right now there's no other state that comes close in terms of the number on D1 rosters.
I would agree with you that "the vast majority of MN high school teams would...be chewed up by most of the US club teams". There is a HUGE talent disparity between the very best and the very worst high school teams, but then again there are 117 varsity teams in just the one state (compared to a far fewer number (?) of club teams spread out all across the rest of the U.S.) so this is to be expected. But there's no denying that the large number of Minnesota high school teams (varsity + JV) affords a lot of girls the opportunity to play the sport while also representing their school, and there's something to be said for that. The system also gives a very respectable number of the truly elite players the opportunity to play for the USA U18 team, as we've seen in recent years, and that's pretty cool too.