After centuries of building, it may be too late to abandon Imperial units. E.g. How to replace that 5/16 nut on your old hay rake? Literally billions of things

After centuries of building, it may be too late to abandon Imperial units. E.g. How to replace that 5/16 nut on your old hay rake? Literally billions of things exist in Imperial units. It's commercially ridiculous to suggest that's going away. So then, either two systems (the worst outcome) or try to switch and your business fails. Btw its 'simpler' is such a dumb reason - simpler for whom? Why is decimal naturally any better than anything else?