That's a fantastic question!!
For a multi-piece beadlock (other than Hutchnison), the outboard hump isn't needed since the backing ring/plate the rock ring bolts to lives where the bead hump is on a single-piece wheel. The bead hump is "replaced" by that backing ring/plate (the one with the 32 threaded holes in it)...then when the rock ring is bolted to that ring/plate, it "sandwiches" the tire between the ring/plate and the rock ring...so there just isn't any feasible reason for the hump to remain.
In order to maintain DOT compliance, you MUST follow the Tire and Rim Associations Standard for wheel design. From the TRA book and website: These Standards include tire designations; tire load ratings and dimensions; approved rim contour(s) and valve(s) for each tire size; rim contour dimensions; valve dimensions, among other Standards.
Since all multi-piece (other than Hutchnison) completely destroys the rim contour and dimensioning, by definition, they cannot be DOT compliant.
B.A.D. Wheels, on the other hand, don't touch the bead profile on either the inboard or the outboard sides of the wheel. We fall perfectly within the approved rim contour(s)
and the rim contour dimensions
set forth by the TRA Standards. We can do this because our locking elements don't rely on external sandwiching of the tire like multi-piece beadlocks do, but rather, we internally lock the tire to the wheel, never needing to touch the bead hump contour
That's the reason you can remove our Sacrificial Rock Ring in a few seconds and replace it with a Dynamic Balancing Ring or other accessory without airing down or removing the tire from the vehicle. Also, due to the locking elements being inside the pneumatic chamber, they are completely protected from the elements and any damage occurring in all conditions. There's nothing quite like having a maintenance-free beadlock!
You can see in the attached picture that we retain the bead hump, and how the locking elements work on the inside of the pneumatic chamber to lock the tire to the wheel. You can also see why you can remove the Sacrificial Rock Ring and not worry about messing with the integrity of the beadlock.
Another fact is that all beadlocks (except the Hutchnison) still retain the inboard bead hump - without it, your tire would easily lose that inner bead/seal since there wouldn't be any mechanical way to keep the tire bead in place.
I hope that answers your question. If not, let us know and I'll put together some graphics showing how multi-piece beadlocks work in comparison to ours