sorry, but stumpjumpers don’t even have really low BBs, it’s your riding that’s to blame.
but 5mm will make a difference PP.. I’ve been running 165s on my lowest bikes for years and would never go longer than 170 on an MTB crank.
What he said…
175mm cranks are “too long” (if you go by the correct way of working out ideal crank length) for about 80% of the MTBing public anyway. Far better would be for any medium sized bike and below to come with 170mm cranks fitted (and say XS size with 165’s). Spesh do fit different crank lengths on different sizes in some bikes, but not in all, and most Mediums come with 175’s iirc.
Anyway, correct shock setup, some 170mm cranks, and some slimmer pedals can make a difference… But it’s mainly up to technique to dial out. I used to hate riding a bike with a low BB cos I wanted to pedal through everything. Now I wouldn’t ride a bike with a tall BB for love nor money, bikes with low BB’s handle so much better, you just need to learn where to pedal and where not to, and buy some tough/slim pedals!