That's not really true. Pretty much every year a player as good as Debrincat is drafted in the 2nd round after the 39th pick.
List of some notable players drafted in the 2nd round after the 39th position by years :
2000: Paul Martin
2001: Cammalleri, Pominville
2002: Trevor Daley, Duncan Keith, Jiri Hudler, Johny Boychuk
2003: Patrice Bergeron, Shea Weber, David Backes
2004: David Krejci, Brandon Dubinsky
2005: Paul Stastny
2006: Jeff Petry, Lucic
2007: Subban, Wayne Simmonds
2008: Derek Stepan
2009: Orlov, Tatar, Silfverberg
I would say in 2001, 2002, 2003, 2004, 2005, 2006 and 2007 there was definitely one player as good as Debrincat drafted between the 39th position and the end of the 2nd round. 2008 is debatable but this is probably because i'm not a fan of Stepan he had a couple fo 50+ points seasons.
I would say out of this list there's at least 11 or 12 players as good as Debrincat in 10 years. So roughly one every year between the 39th position and the end of the 2nd round. There's some very big names in this list btw.
At this position your chance to get a very good player are still significant and probably between 3% to 5%. That's 3% to 5% more than Shaw cause Shaw is not a very good player.
I really don't understand how some people can see this trade as a good one. Shaw is a replaceable player. You don't give a 39th pick for a player like that specially if he's not under contract, his current team don't want to sign him and he's asking for pretty much his UFA value while not being UFA.