Eh, it's still used today for shortwave and it's nearly trivial to make the basic circuits.

WRT to shortwave, there's a certain coolness to a technology that allows you to make world wide 2 way communications without out the aid of any intermediate node with equipment that can fit into the palm of your hand (a small CW (Morse code) transceiver and wire for your antenna).

yeah I agree, but these concepts form the basis for our modern communication systems so it worths learning them.