I have tried to visualize how those things can do any good at all.
Marketing says they give you a massage. I can't see that, unless they have little motors in them.
Marketing says they provide ventilation. I can't see how air could get past the first row of beads.
Marketing says they reduce pressure points. With half the support surface it seems pressure at the beads would be doubled.
It looks like it would be similar to sitting on gravel.
I think it is all marketing and no engineering, but I have never sat on one, so what do I know.