As the others have mentioned, it’s about following standards. Like if you specify a design for a plug using standard measurement units, people can then make plugs that plug into that using whatever measurement and calibration tools they want because they all generally follow standards.

It would be like if the government released some device that was meant to be repaired by anyone but used some proprietary Apple screw head for all the screws. That’s not repairable by anyone, that’s only repairable by Apple customers.