I agree wholeheartedly! Many years ago
I did a bunch of experiments, separating the grind on shaken analytical screens, looking at the particles in the light and scanning electron microscope and trying to figure out what made the best grind for espresso. It seems every grinder makes a "bell-shaped curve" of particle size distribution and for espresso the best grind seems to have a wide range of particle sizes (but no boulders). I never thought to dispose the fines because I was only interested in espresso and they don't usually get through the basket. I just tried an AeroPress cup with the fines sifted out and it was very clean and tasted excellent (Ethiopian "wild-grown" Kaffa Forest roasted just to second crack). The problem with the fines is not only that one has mud in the bottom of the cup, the whole cup tastes a bit muddy with them in there.
Thanks for this stimulating discussion, Tom.