My existing planer and ramps, as seen in OP have sat on the concrete floor for the past ~4yrs without an issue. There are weight plates holding the original 3/4 ply from warping ,but it conforms to the existing concrete slab.
I understand the technicality of your suggestion, however pragmatically it has worked for me. If you look at my ramps, they are each supported by 4-bolts and each is height adjustable. The only thing that needs to be flat (not necessarily level) are the ramp boards themselves. Those ramps are adjusted to the planer’s orientation only, and the table or concrete floor upon which they sit is of no real consequence unless there is a major change such as the concrete buckling and shifting. If such an event occurs, then the ramp adjusting bolts would need a new adjustment. This setup is quite flexible in that regard. Thanks for the thoughts though. I tend to do that also, more often than not.