To be fair - while you may be sick about hearing it (and I do agree with the fact that it is not an excuse for other people slacking off). people do look to their best players, etc for guidance, how to act, how to train, etcetc etc. Even if they don't want to be that person and I don't think it should be dismissed.
I get that people go all "lol Jeff O'Neil" but he always states that he learned how to do things from the more talented players (as well as the older vets) in Hartford/Carolina. almost every single hockey player i hear on the radio talked about how they did it. (including current NHLers like Stamkos (MSL/Vinny), and Subban, etc).
O'Neil also stated that he didn't take it all to heart. and he blames it on himself, but that's with him having a good influence, and he's said he can't even imagine how he'd be had he not had that (probably out of the league faster than anything).
I'm not going to be sitting here saying that Kessel would be a negative influence nor would that give someone the right not to do their own best, however - if you are a rookie and you look towards your best/talented/most played player and see how they act, carry on. it can make an impact and I dont think it is out out of the realm of possibility to want people coming in to have the very best in that locker room.