[paulddraper]

Gunpowder and ICBMs were also in use at the same time

I'm claiming the technological backstepping is not nearly as drastic as the GP implies.

[thaumasiotes]

But you listed a completely irrelevant gap. The gap of relevance is the one between automobiles and now, not the one between carriages and automobiles. If automobiles were the transport technology of 1890 and carriages were the technology of 1889, then devolving to carriages puts us back to 1889, regardless of when horses were invented.