I don't know why manufactures bother with pressure recommendations like that. If you're riding trails, 40 is waaaay too high unless you're quite heavy. I'd think something in the 20s would be appropriate for most riders. You will feel benefits of lower pressure of you're set up tubeless.
for reference, I'm 160 pounds and using 29x2.3 tires (tubeless, naturally) on rocky terrain. Usually 20psi front and 24 or so rear, and mine are on the high side.