You're coming up with a narrative about a narrative that never actually happened.
There definitely are posters pushing the "Kostin isn't worth 2 million and is a bum who will fall apart in Detroit" angle as soon as he decides not to gift the Oilers a discount and simply wants the same money that McLeod got (a guy who's production he equalled and then surpassed in the playoffs).
Dude is a good player and we're probably going to miss him. He saved our ass against LA, if we had lost in the 1st round of that series, the entire narrative around the franchise shifts entirely to a franchise trending backwards with McDavid/Drai probably looking for an exit ramp.
It's too bad we lost this player, I think if he was given time with McDavid or Draisaitl he would score 20+ and probably a lot more easily than Yamamoto or Puljujarvi did. Those guys looked like their hair was on fire every time McDavid or Draisaitl gave them a gimme feed, Kostin would just bury those kinds of feeds.