Could you provide a source for this? This is the first time I"ve ever seen anything suggesting any teams, let alone most, have made this concession.
It's a really good pick, no doubt, but I think he approximately where he was ranked. Some had him considerably higher, many slightly lower.
So the question becomes whether taking a player approximately where he was ranked, late in the first round, "a huge steal?"
At
2015 NHL Draft Prospect Rankings you can see 12 different pre-draft rankings.
Craig Button at TSN had Boeser #9, both Ryan Kennedy of THN and Shane Malloy of Art of Scouting had him #14, McKenzie and Future Considerations 26th, McKeens, MacDonald of THW and Damien Cox on Sportsnet 27th.
Ryan Pike's final rankings at The Hockey Writers had him at #26 and said "Craig Button really likes this kid, ranking him 8th in April, but every other service has him in the late first round."
https://thehockeywriters.com/2015-nhl-draft-alternate-rankings-final-edition/
The 2015 first round is looking spectacular. A little over three years in and McDavid, Eichel, Marner, Provorov, Werenski, Rantanen, Barzal, Connor, Chabot and Boeser are all looking like stars and a few others are looking solid, plus 2nd rounder Sebastian Aho already has 49 and 65 pt seasons to his credit and is over 1 ppg so far this season.