Rubbing compounds are designed for a machine with a far more agressive action. Without this scrubbing rotary action, the compound cannot remove any significant amount of material, which is the purpose of rubbing compound. This action is also needed so that the compound 'breaks down' during the buffing process. As the compound abrasives break down into finer and finer pieces, the compound transitions from 'cutting' to polishing. Without this agressive rotary action this just does not happen. The result is poor removal of oxidation and poor surface finish.

Actually, as a professional refinisher I can tell you that orbital buffers are not of much use at all. Before foam pads came along, an orbital buffer was the only way to get a swirl free finish when buffing really soft new finishes like some clearcoats. But with the advent of the foam pad you can get a swirl free finish on all but the very softest finishes with a rotary buffer. Remember that a rotary buffer is like 10X faster than an orbital. For those few times in the shop when we feel like we need an orbital for that final touch, we just use a wool buffing pad on a air DA sander. The DA is much smaller and more nimble than those big electric orbitals anyway.

The caveat is of course that if you are unskilled with a rotary buffer you can screws thing up, even get hurt(I knocked myself out cold with a rotary buffer, once. Yup ) It's about impossible to screw anything up or get hurt with an orbital buffer because they basically don't do much.

I think that's why they got so popular; retailers are not afraid they will get sued since you are unlikely to ruin your finish or whack yourself in the head with an orbital no matter what your skill level, so they began to push them as the latest and greatest thing. Just a new way to sell surplus washing machine motors

IMNSHO

Jimbo