https://en.wikipedia.org/wiki/Mead%E2%80%93Conway_VLSI_chip_...

I'm guessing is what they're really talking about. Which is not about NAND gates.

Just to add a bit, but modern digital circuits are almost exclusively MOS, but even the "complementary" bit isn't universal in a large IC.

I believe you're not ignorant. But many folks probably lack the process knowledge (CMOS) required to understand why :-)