I think it's more complex than that. They weren't goons like, say, Florida is now. But they didn't wilt (like the Leafs do) when a team tried to play a mean and heavy game against them. Crosby can play a low key dirty game... And that is a must in the playoffs. Matthews rarely gets mad and uses his size. Nylander and Marner don't have a mean bone in their body. Add Tavares to that too.
They need a couple of guys (not 4th line clowns like Reaves) that can play. Skate, hit, score a bit, and if need be play nasty and beat you senseless. This is a game of aggression and the Leafs don't strike fear in any opponent, from a physicality standpoint.