I'm wondering if it's more of a defensive responsibility thing? Not a shot at Dach who is the team's most skilled forward and is no slouch in this area, but Cozens is faster and plays a harder game.
In terms of keeping them together, they are probably the team's two best forwards and they have complementary skill sets. Nothing wrong with loading up the first line, especially on a team this deep. Dach is a big-bodied playmaker, Cozens a skilled, powerful pace-pusher, Quinn a sneaky finisher who plays both ends and makes plays in traffic. On paper, it's good mix.