I take exception to this. I think there is some proof in the numbers. I've done no research on this but I can't think of another player entering free agency for the first time, coming off a career year, who signed for only a $1m increase on the yearly salary from their previous contract. To me, that shows Marner was overpaid on his previous deal.
There are two great comparable players in Point and specifically Rantanen. Marner received $10m more than Rantanen over the same time period, signed the same year, and I don't think it's a coincidence the signed identical 8-year/$96m contracts this past offseason.
(*I won't litigate what McDavid did. He clearly could have received $17m or more on his free agent deal if he so desired)