I agree that it is your opinion (and mine can be different) but the 1Dxiii/R6 users seem to be okay with 20mp for sports/action.
Sports/action photographers are probably shooting for magazines or newspapers, where a resolution of even 12MP is more than enough for a full page image. Most sports pros will also be in a position to buy or hire very expensive big whites. Furthermore, as pros, they'll be highly skilled at tracking and framing fast moving sports players, so can get away with less cropping.
I'm a hobbyist wildlife photographer, as are many here. We need more affordable options, which is where a combination of high MP sensors, shorter and more affordable lenses, heavier cropping, and lower skill levels at tracking subjects becomes relevant.
Like I said, I'm just giving my own perspective, and for me, 20MP is "measly". I can just about justify and afford the cost of an R5, a RF 100-500mm and RF 800mm. But no way am I going to buy a 1DXiii, a 400mm F2.8 and a 600mm F4.