I think people invest more into the Steve Sullivan/Martin St. Louis cautionary tale more than actually talk about the pros and cons to Robertson's game. He's great hustle and desire, good practice skills with the puck and an unusually devastating shot. But he's small, weak as hell on one on one battles, doesn't have high IQ to read a play other than to go full throttle 110%, and can't figure out how to get open to use his shot.
No one held him back so he couldn't take the McMann progression when this team has zero secondary scoring. The fact that he's stuck in 12th/13th forward with Reaves just says a lot about how his game isn't well suited to do all that much.