In all fairness, even tubular metal frames are very directional in the loads that they can bear. But fiber layups (including carbon) aping the form of tubular metal frames are more so, to the n-th degree.
I think some early carbon monocoque designs (eg. Trek Y) were on a better track in terms of how to use carbon (not to imply that they were good bikes) by not trying to ape the form of tubular metal frames. And some components were either better left as metal structures (eg. rear triangles), or by going monocoque (eg. '95 Cannondale Super V, again not implying that the particular implementation was at all good)
I'm not totally averse to carbon on a MTB, but for the higher forces an eMTB can be subject-to on impact in a crash just by virtue of its own mass... I'd be a little wary. Maybe on something like a Levo/Kenevo SL.
I still think there's a lot left untold about this particular story, though.