Other than tanking for Bedard the Habs’ draft (day one) made zero sense. Like you suggest, Dach is already a bust. And Slafkovsky has a definite bust candidate. The could literally come out with less than what they went into the draft with - like you say, a 21 year old 20+ min Dman.
Slafkovsky is already competing against men and plays a very well rounded game. He may not be the best player from this draft eventually, but he's going to be a very good NHLer.