Using awkward units of measurement that have little compatibility results in a multiplication of even more awkward units. If you don't have a good, easy way to

Using awkward units of measurement that have little compatibility results in a multiplication of even more awkward units. If you don't have a good, easy way to convert between acres and square feet, you instead need to imagine some unit custom built for the application. So rainfall is typically measured in inches, crop areas in acres, simple we will just invent an acre-foot and now people can convert their rainfall needs into water amounts. Maybe. There's probably a lesson for system design here.