Attempting to draw large circles perfectly with just a length of string can transform even the coolest woodworker into a muttering grump.
Drawer bottoms must remain free-floating (not glued to the drawer frame) to allow for expansion and contraction due to changes in humidity. But often the bottom will develop a rattle.
Clamping any long, narrow object on edge requires a door buck or other specialized equipment that most home woodworkers just don't own.
Exposed handsaw blades are a triple threat: They can injure careless hands, they inadvertently mar wood, and they damage easily.
When you apply pressure to boards or sheet goods that you're attempting to surface-laminate, the stack wants to slide around.
Before a project reaches completion, it can suffer a lot of dents and dings in the shop. Cabinets or bookcases built of plywood often end up with chipped face veneer at the bottom from being shoved around on the shop floor.