Did Matthews have multiple concussions a year or break his leg on a post? The time missed between those 4 players during their peak is pretty incomparable, Matthews has missed a handful of games with wrist and shoulder injuries vs missing more than half the season multiple times like Crosby Malkin and Stamkos in the middle of their peaks.
After hitting his goalscoring peak in 2009-10, Crosby played 41, 22, and 36 games the following 3 seasons.
After hitting his goalscoring peak in 2011-12 Stamkos played the lockout half season at a similar pace and then 37 games the next season before breaking his leg in half.
Malkin hit his goalscoring peak in 2011-12 as well and followed it up with 5 straight seasons where he either didn't hit or didn't pace for 70 games played.
If Matthews gets demolished by injuries to this extent while the league has an overall decline in scoring and PP chances that Benn can win an Art Ross with 86 points then yeah I'd expect his numbers to drop off like the players mentioned above.
If you look at late peaks like Kane, Marchand, and Kessel, you can see that they have a few things in common. None of them have missed significant time to chronic game altering injuries and they had their late peak years immediately after the mini dead puck era ended (2016-2018 for all their best seasons).
Guys who score a lot play a lot, guys who play a lot are more likely to get serious game altering injuries earlier in their career than guys who don't play a lot. This could happen to Matthews or McDavid tomorrow, but if it doesn't they are likely to defy that curve through their mid-late 20s.
