Just roasted then crushed cocoa beans; & the best way to get the fiber on.
Each step eliminated in a chocolate’s lifecycle reduces the margin for error, so that each remaining step has to be even more precisely calibrated & finessed. In the case of Nibs, this places a premium on bean selection / post-harvest techniques, then roasting & winnowing – the last, that crucial act of removing papery husks, or shells, encasing the beans. Left on, husks can result in ‘off’ bitter flavors.
With only Nibs, the maker hangs out there with less cover.
For example, one of the final stages in chocolate bar making is the conching so vital to reducing volatile oils & mellowing flavor. That can be great in some regards, but it can also serve as a screen to hide behind. Ditto the coddling in of components from sugar & lecithin to vanilla, among other flavorings. Without them the upfront nature of cocoa comes full on.
When done right, it puts the buds (taste-buds, that is) closer to the source & provides a clearer window on the distance chocolate travels from its beginnings as a cacáo seed.