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, non-metric users will ask metric users 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?
The problems with that are:
hardly anyone knows the conversion factor
other people aren’t going to do the math in their head
them == everybody in this case. Practically, nobody is going to do what you suggest - instead, non-metric users will ask metric users 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?