Translation: Not a single player left a penny on the table
Welcome to the NHL. Guys want to get paid. Especially young guys. And they want to be paid for future production too. It's no different anywhere else.
Marner receives a ton of criticism because his camp went really public and sounded greedy, and Marner has yet to live up to his demands. He wanted to be paid like Matthews but has not come anywhere close to Matthews' level of play since (just like he never came close before the deal).
If Marner was playing as well as Matthews right now, then he likely receives a lot less criticism, much like Tavares/Matthews/Nylander (if there is any contract criticism regarded them, it is usually directed towards Dubas). That is because they have exceeded, or at least met, their contracts.
We also likely win multiple rounds and are flirting with winning a Cup rather than losing first rounds constantly. Marner has progressively performed worse in the playoffs since he put up 9 points in 7 games, and was actively a negative contributor this year to the point where it even affected Matthews' play. Hyman is no different, but nobody blames him because he is not a core player and the expectations are lower, which is fair. However it is not like he has been any help in the playoffs recently either.
Marner's criticism is completely warranted, but the idea that only Leafs' players want to get paid or won't leave money on the table is a myth. We just want our young guys to live up to or exceed their contracts like every other young high quality RFA who has wanted to get paid has done in the past and make it lead to results. That has not with Marner (yet) unfortunately.