I think the rocker could lift heavy weights to store energy with less energy. Like an upside down pendulum. The rockers could have drop down height stock that allow you to use the weight of the weight to lift.
A useful device / concept.
In a way, like a lever (long end) can trade a lesser force aplied over a greater distance in exchange for a greater force expended over a shorter distance. Before losses due to friction and so, the work done on each end of the lever is the same. Its easier with a lever but the work done / energy expended is the same as with out the lever.
Rocking an object may make it "easier" or just plane doable as opposed to not doable. But the energy inputs in a series of light pushes (the rockng input) will together total up to the same amount of energy as if done in one big push.
floor
My thinking is if you have little wheels it take a lot of force to go over the 45 degree incline but with super big wheel it should be less. I think the weight is at an angle that aids in the lift.
There are YouTube video of this guy that lift heavy weights by lifting one side then putting stock at the center then lifting to other side and doing the same thing. He lift and also pivot heavy objects.