You are probably thinking of narrow-wide. NW rings are incompatible with front shifting. No longer dropping the downshift and grinding the upshift are not the original reason for 1x drivetrains, but it was a nice side effect that drove the proliferation. But you can't have that and also odd-numbered tooth counts, or shift gates. Skip tooth was an ancient single speed thing. Early chains did not have rollers. The inner links were a stack of plates, or solid. When googling for a photo of a skip tooth, I discovered they are now trying them in go-karts - obviously insane, but you know how fads go. Meanwhile don't even try googling for block chain, hahaha