McDavid didn’t win due to a multitude of factors:
-He was much better the year before, so it was seen as a somewhat disappointing season by his standards
-Matthews scored 60 goals, which hadn’t been hit in 10 years, including an unofficial 50 in 50
-Matthews was seen as the better defensive player, getting decent Selke support
-Matthews was barely behind in terms of points per game (1.54 to 1.47)
So, with the goals added in, Matthews was seen as having similar or better offensive production, which, combined with being better defensively, is why he also won the Pearson
Ultimately, the Hart mostly goes to who is deemed the best player or who has the most outstanding season. It’s actually pretty rare that relative value comes into it and is usually because the actual best player missed the playoffs, like in Hall’s year. How good their closest teammate is seems to be brought up in fan voting a lot more than by the actual voters. McDavid didn’t stop Draisaitl from winning in 19-20 despite having a better season. And considering Makar is having a better year than McDavid as well, it makes no sense to factor it in. With MacKinnon having won last year and both teams being in similar positions, it will mostly come down to who the voters think is better. And Draisaitl’s goal scoring will probably factor into that the most.