Secondly, as it was already pointed in this thread, there are other ways to manipulate - for example by omitting some facts or simply rephrasing them.
To give you an extreme but real life example, recently in Poland there was news about Robert Biedron, left wing politician who rescued a two year old boy and his father from a burning car, then according to other media he just allowed them to wait in his car before police arrived (and I can't honestly tell which version is true - this kind of supports your point), but there was also a headline that translates to "Car crashed and burning with a 2 year old child on board. Robert Biedron involved". While this obviously gives a completely inverse impression on the viewer, technically this is not a lie - all the information in that headline is true and 100% correct. Penalizing lying on the internet will not stop manipulation. Maybe just make it a little bit harder forcing the manipulator to be a bit more creative