Yep, I think they must use strength to smoothly determine the range of a throw...and to be honest, even with 18 strength, you should not be able to throw anything really weighty (and a regular 70-80kg humanoid is not light...) very far at all. In all my years of PnP D&D, I have never encountered anyone throwing an enemy - unless you count grappling (throwing to the ground?) . Bull rush is sensible: you have momentum behind your dash. But picking up a heavy dead weight and flinging it 10m? Unless you're a giant, that just doesn't make sense.
