I would obviously hope you're right, but when I watch both (admittedly I watch Matthews a lot more) I usually come away thinking MacKinnon is a better player, and it's not just based on raw points either, it's their actual skillsets and offensive IQ where I can honestly say without much doubt MacKinnon is better based on observation alone, and he just happens to produce far more points on top of it.
Mackinnon is fast and flashy, which tends to draw the eyes and stick in the minds more (Marner anyone?), and we tend to equate those attributes to offensive skill even though there is so much more to it.
He is also on a stacked line, and it is so, so, so much easier to win the eye-test battle when you have a line that can be so dominating that it covers the deficiencies that those players have, and the opponent has to usually skate the entire ice surface tired after you make a mistake. We are starting to see just how much a strong line can tilt the ice now that Matthews and Marner are together, and they don't even have a 3rd high-end player with them like Mackinnon. It's also so, so much easier to look favourably on aspects of his game that you would otherwise overlook or criticize, once he's already scored with his league-high PP time.
Points per 60 are not linear to getting more ice time, although I agree that generally a player will score more with more time especially on the powerplay.
I keep seeing people claim that "P/60 is not linear to getting more ice time". Thing is, nobody ever wants to provide evidence of this, because there is none. Obviously there is a point of diminishing returns, but all evidence points to that point being beyond the ranges of ice time we are discussing.
I did 3 experiments testing the relationship between average ice time and P/60. I can go into more details if you'd like, but
in all 3 of the experiments, there was actually an INCREASE in P/60 as average TOI/GP increased. Even I did not expect that going in (especially when I pushed the experiment to the very highest TOI seasons in the cap era), and I expect there are external influences that affect this (which is why I maintain my stance of a neutral effect instead of going around claiming positive effects), but it only solidified the fact that P/60 doesn't see any statistically significant drop due to increases in TOI within the ranges that these star players play.
The fatigue argument never made much sense anyway, since the majority of ice time differences that significantly affect production between superstars is PP TOI/GP, which are incredibly easy minutes to play.
I just don't see what offensive skills Matthews has over MacKinnon other than his wrist shot which MacKinnon is even not far behind in.
He's bigger, stronger, has better puck possession, has better stickhandling skills, he goes to the high-impact areas of the ice more, he has a
much better shot, and unlike Mackinnon, he has shown that he can produce without a stacked line. And he's only just scratching the surface of his prime.