It doesn't stop at gravity either. Virtually everything in the game world is moving via acceleration. If you were going to do this in a consistent manner you would need to do this for every single physics calculation for every single game world object.

You are correct that you would have to profile it to determine how much of an issue it would be but it sounds like potentially a lot of deadweight to add to the game. Especially since when games slow down it is often due to having a lot of objects in the gameworld simultaneously.