One I don't think I've seen mentioned is scale. After some comments that there's no way exceeding small torque values like 15 in-lbs could break a fastener: remember how small the fasteners are. I broke a screw in a USO base because I hand tightened before getting the torque wrench on and... it was a very small screw. Snapped right off where it should when over-tightened.
Substrates and fastened items also matter, as partially mentioned. And, it doesn't mean the components are badly designed. I sometimes work with (in design, etc) electronic components on big machinery. They often have the torque rating molded right into the electronic case in the hopes techs will notice, because even the first hand-tighten in the manner of bolt-engine-together will destroy the electronic box and often the seals, the connectors, or even the PCB inside.