Thornton wasn't capable of putting up those points in the clutch and grab era either
He won his MVP in 06 when the league averaged 3.08 goals per game, this year the average is 3.07, the scoring environment is entirely comparable to when Thornton hit his apex and McDavid is still eclipsing it
I won't get into the stylistic comparisons as they are mostly immaterial, how players accomplish their feats isn't as important as whether or not they do
The style of play in the current NHL is dramatically different than when Jumbo won MVP. They may have similar scoring averages but I think you need to look closer at the underlying stats to see where that's coming from. PP, 5 on 5, etc.. Style of play of course matters. Robataile is (or was) the leading goal scorer at his position in NHL history but he scored most on Gretzky's wing. There are a huge number of players at his position (LW?) I would choose before him if given the choice. Obviously over exaggerating for the point. So yeah, saying that whether they do is more important than the how is false.
To me the comparison is similar to the great Avs teams who had Sakic and Forseberg. Both produced at insane rates but Forseberg was the horse that pushed them to multiple cups. He drew the #1 defense & checkers from opposing teams. Sakic of course then took advantage of 2nd tier defenders when they were on different lines. Jumbo is more of a horse and McDavid is the fast player.
Also another difference IMO is that Jumbo didn't have a teammate that rivaled his production without being a product of it. McDavid has Drisital who on some nights seems as good and sometimes better. The sports writers used to say that Jumbo made his wingers rich. Is McDavid doing that? Curious how dominant he is when Drizsital isn't in the lineup. He certainly doesn't look like the best player in the league when he plays the Sharks.
McDavid is great and over time maybe he is better. He's certainly built better for the current NHL which is far more geared toward faster players than back when Jumbo was MVP. But the difference isn't as dramatic as some here make it out to be.
Regardless, obviously we see it differently so to each their own..