One word: FOD
If your tool breaks, and we all know that they can, you have to find all the parts of that broken tool. Chip the corner of a flat screwdriver, you have to find that chip. Now you are wasting hours or days looking for it, and you are grounded. Or the chip ends up in the cables, engine or flight controls, now you lost the aircraft, crew, and classroom of little kids that the airframe collided with in uncontrolled decent. All beacuse of a chipped screwdriver. I know that seems extreem, but this is what we all deal with in aerospace.