trying to develop the best intercompatible standard on the open market.

How would you, actually, achieve this? How would the open market develop a good intercompatible standard that then everyone would use?
This is the approach taken with the automatic cargo wagon couplers, the transition been going on for about four decades now and there are basically zero results. The open market cannot seem to achieve any results whatsoever. There's always some company that does its own thing. Such as Apple was with phone chargers.

it is generally a bad idea to mandate a specific technology

Why is it a bad idea? Can you give any examples of where it has been a bad idea? I can recognize a case where it was a very good idea: USB-C.