That excuse isn't going to work for Allen any better than it worked for Marino.
I wouldn't call that the only reason. Mahomes is a great QB. If he retired today, he'd be widely considered a top 5 guy All-Time. Patrick has proven to have the ability to adapt to what a defense gives him. From slinging the ball all over the field for 5,000 yards and 50 TDs, to dinking and dunking. He just gets the job done.
They put the stats up of he and Mahomes over the past 4 seasons and the 21 additional turnovers for Allen is jarring.
Allen is still great and likely a future Hall of Famer. He's still got time to collect a couple of rings and MVPs.