I mean this view of how each player was viewed at the time seems either very charitable to MacKinnon/almost solely on the Hart voting record to the exclusion of all else. As you yourself noted, beyond McDavid, there is Kucherov, Draisaitl, MacKinnon's own teammate Makar, and of course, GUCCY Matthews. Not to mention some other defensemen you could add, or Vasi even in this period.
So sure, if you'd prefer Messier or LaFontaine or Hull or Bourque (I'll even add Roenick in the early nineties) over Yzerman, I get it. Different strokes and all, but I don't see how it's too different from MacKinnon with his peers either.
However, as I posted earlier, the broader record and general zeitgest of the time is fairly clear in the Gretzky/Lemieux/Yzerman thing. Solely going by Hart voting seems to be a quite limited historiography and hardly fully reflective of what was the vibe of the time.
Ignore 1987-1988 and 1988-1989, where it's very clear. Look at after 1989-1990. Yzerman may not have factored in Hart voting, but he was straight up called by The Hockey News Yearbook as the third best player in the NHL after Gretzky and Lemieux (Messier was put after them) and the Hockey Scouting Report after that year said they wouldn't argue strongly against Yzerman being the best player in the league (meanwhile a guy like Ray Bourque who was a very close runner up to Messier was called a top five player).
During the 1990-1991 season, Bobby Hull himself mentioned that his son doesn't need to take a backseat to "the Gretzky, Yzerman, and Lemieux's". He didn't mention Messier or Bourque or LaFontaine, even if sure, maybe they also deserved to be mentioned. After it, The Hockey News Yearbook still called Yzerman the third best center in the league, after Gretzky and Lemieux, this time they used center instead of player though, the great Brett Hull and all.
For comparison's across sports, well, Yzerman's company is again super flattering, this from a St. Louis paper itself:
View attachment 893334
Yzerman's star may have faded a bit in 1991-1992 in the media, he wasn't kind when he said he'd refuse to report to Quebec just like Lindros, but you can still look through like hockey cards and magazines and whatever at the time. When Coffey came to Detroit right before the all star game in 1992-1993, what else did he say, but getting to play with the top centers in the league Gretzky, Lemieux, and now Yzerman, who was "just like them"