Nothing to do with suspension. It was engine/trans longevity issues. Look at qualifying for a better picture.

Look, suspensions can be sprung by a coil, a leaf, torsion, or air spring. This concept has not changed much in a couple hundred years. The contact patch on the road could care less about what is appliying the force so long as it does not override the available traction of the tire in use but maximizes it at all available directional changes. At that point, then the geometric layout will either support the application of force or will impede it. Damping control will dictate how fast or slow the force is applied. The only real thing that has changed between the 70s and now is our ability to better control the grip at the contact patch, the damping and its application of force, and perhaps the size of the overall spring package.

Coil over kits are nice because they are compact and light. That is the biggest advantage over a coil or torsion spring. They DO NOT apply force in any better manner than a properly rated and dampened coil or torsion spring.