The problems with that are:

1. hardly anyone knows the conversion factor

2. other people aren’t going to do the math in their head

That’s on them

them == everybody in this case. Practically, nobody is going to do what you suggest - instead, they will ask people who use metric to do the conversion for them. And why should we be responsible for doing the work when they are the ones who refuse to use the system that 96% of the world has adopted?