Worse: A missing standoff under a critical power plane can cause intermittent shorts. I’ve seen a 6-drive RAIDZ2 go poof because the builder used nylon standoffs everywhere, breaking the ground path.
Hand-tightening works for test-fitting. Brass standoffs have shallow knurling for finger grip. nas standoffs
One pro tip: Thread a spare screw into the standoff before installing it into the case. This gives you leverage and prevents over-tightening. A NAS runs 24/7. Vibration from hard drives can loosen cheap standoffs over months. Loose standoffs = floating motherboard = random crashes or USB dropouts. Worse: A missing standoff under a critical power