Ok
I thought of a much better way to explain it. Imagine you are trying to hold the tank, and its half full. You are holding the mounting tabs on the side with your hands, and gas is sloshing back and forth. That would be tough. Now imagine you have the straps around the bottom of the tank, and you are holding those. It would be a lot easier, and would have a lot less stress on the tank itself.
Maybe I am just typing away with not much meaning, but at least it ate up a few minutes for me
Shawn