simple


QR dropouts are fixed position, there is nothing to slide

horizontal dropouts (for adjusting chain slack) can slide, need bolts
or axle stops


no QR will eclipse a grade 8 bolt in tightness
if you tighten the bolt enough. unpossible. qr just cannot do what screw threads can do
for compression force

if you have horizontal dropouts and a qr and it doesn't slip, U are lucky but most peeps need
a surly tuggnut or something similar.