But this is a different definition of "grind". After spending an hour practicing your aim on a specific map, your aim will actually be better. That's not any different than spending an hour practicing shooting hoops from a specific angle / distance, or spending an hour practicing musical scales.

I think when most people talk about "grind" in games, they mean activities that are genuinely only time-wasters. You don't gain any skill (other than patience) from killing your hundredth goblin or clicking "harvest" on your hundredth field.