You don't know that. Players getting more minutes are getting different deployment. For example, the defenseman who leads a team in ice time is generally getting deployed in the most difficult defensive situations. You can't just at look at points per minute in a vacuum and make an extrapolation that with more minutes he'd score at the same rate.
Example: By your points per minute theory, Jason Spezza was the 3rd best scorer in the NHL last season, and should be paid on a Marner, Matthews, Panarin level.
You think if he received Marner, Matthews, and Panarin minutes he would have kept up that pace?
You think Spezza deserves a $10M contract and that if he brought up his points per minute he wouldn't be laughed at by the arbitrator?