I do know that isn’t true for yourself and some others. You also know it is true for a solid handful as well.
There was a time we thought McDonagh had Norris potential, though admittedly, we also all know true defensive D never even get nominated. Better is a relative word. Fox is far more offensively talented in a way that goes beyond the physical ability to handle the puck or weave a pass. His IQ and vision and game sense with the puck are superlative. A large part of his positive defensive impact does not actually happen inside the D zone. It happens by moving the puck the other direction. McDonagh was a hell of a defender and still managed to put up 30ish EV points per year as well as a season with 43 non-PP points. That also happens to be Fox’s career high for non-PP points.
Is Panarin better than Bergeron? Panarin’s broken 95 points more times that Bergeron broke 70. Career high 120 vs 79. Bergeron is in the hall before Panarin, zero doubts. Now, I’m not using that as a comparison, only to illustrate the weight of points. Obviously with Fox and (prime) McD, I think most would agree Fox is better, but just because he puts up points, I don’t believe the gap is nearly what people would think it is. There are other ways to have a massive positive impact on the game, in the case of Bergeron vs Panarin. A career high that’s more than 50% above Bergeron’s career high still can’t close the gap for Panarin. In McDonagh’s case, I’d argue respectable 5v5 numbers, dominant defense, great athleticism, good longevity and 2 Cups brings him closer to Fox’s level than many would care to admit. Just because the points column isn’t as sexy, doesn’t mean he (was) much less effective. Bread and butter looks plain but feeds you better than a box of fancy chocolates.