Well, the 3-point hitch was originally invented (by some guy named Ferguson, I think) to pull a light-weight plow and allow it to drag itself into the ground and increasing traction of the tractor while doing it. Prior to that, the plow had to have a lot of weight on it to dig into the ground, and the tractor had to have its own weight to make traction.
The lifting function was for draft-control. The draft control system servoing the plow height to maintain a constant force on the top link. The idea being that constant top-link force=constant tilling depth regardless of the tractor going over lumps and valleys in the land.
The side-to-side geometry and flexibility was designed to help the plow follow the tractor while turning. The idea being to approximate a virtual pulling point up near the front axle.
So, if you are putting anything but a plow or maybe some kind of blade back there, the 3-point hitch really is being used for a purpose other than whit it was originally intended.
- Rick