It's perfectly normal engineering practice. Camshaft, gearbox profiles, and bearing surfaces in your car have very tight tolerances. A one slightly unbalanced turbine blade in your airliner engine would assure catastrophic failure. etc etc
Is it even possible to discuss anything Elon Musk anymore without 100% praise of his engineering prowess? Every single comment gets down-voted into oblivion, with very few replies. And, due to the "cool off", this prevents any balanced discourse.
It is more an issue of quality control and inspection routines.