Actually quite a few do. Gaudreau doesn't get questioned because he's the best player on his line, and on just about any team he's going to play with a Monahan-quality player. Monahan gets questioned though because he plays with the better, actuallly elite player in Gaudreau. He wouldn't necessarily get that type of linemate on most teams as a lot of teams have better centers, and he can't drive a line on his own to the same degree. Every player who plays with a better player or players gets their production put in context around here. I don't know why so many Oiler fans seem to miss it.
Check out this thread to see how many people question Monahan's totals:
Horvat vs Monahan
Draisaitl's totals away from McDavid are obviously brought down by the poor depth of the Oilers, and he would score a lot more as the best player on his line with the actual top line players he would get on most teams, but it's also obvious that he's in a unique position as an elite player playing with the best player in the world, and he's not going to score as much in an average situation for such an elite player as he does with McDavid. If he's being compared to other star players who aren't in as good of a situation for their production, this needs to be taken into account. I'm not sure why there's such push back against this.