Originally Posted by Dave H

Using mass weight for force results in different results, as gravity changes for a variety of reasons. Using a proper force unit like Newton eliminates that, a Newton is always the same force anywhere. Fairly obscure trivia, the proper mass unit for the imperial system is slug. Although lbm and lbf are commonly used (pound mass and pound force).

Oz-in and oz/in are dramatically different units. Oz/in is spoken “ounce per inch”, and could be used for a stiffness value as one example. Although like above it should be noted as ounce force per inch to be unambiguous.

Hardly messed up if applied correctly. But in casual use, well yes, it is that sometimes.