I came across a line on http://physics.ucr.edu/~wudka/Physics7/Notes_www/node49.html
" If the experiment is tried in vacuum any two objects when released from a given height, will reach the ground simultaneously (this was verified by the Apollo astronauts on the Moon using a feather and a wrench). This result is peculiar to gravity, other forces do not behave like this at all. For example, if you kick two objects (thus applying a force to them) the heavier one will move more slowly than the lighter one. In contrast, objects being affected by gravity (and starting with the same speed) will have the same speed at all times. This unique property of gravity was one of the motivations for Einstein's general theory of relativity"
This does not make sense to me. True, that different masses will accelerate at same rate due to the force of gravity, but that is because different magnitudes of forces are acting on them (a larger force on the heavier body and a small force on the lighter one, from the formula of gravity.)
So how does it violate inertia? It should have only violated inertia if the force acting on bodies of different masses was the same,and yet the acceleration was the same. What points am i missing? Can someone please explain how it is true and how it led to the General theory of relativity?