> It was easy and cheap, before microcontrollers were as friendly to use as they are now.

I got started with AVR microcontrollers with a DIY parallel port ISP adapter: just cut a printer cable in half, solder in 4 resistors and you were good to go :-)

Then spend a ridiculous amount of time re-learning assembly to port the parallel port LED blinking program from DOS to the AVR.

Only needing the few scavenged parts and buying just the MCU was a lot cheaper than buying the "recommended" adapter cable or some eval board, making the whole thing affordable for my 13 year old self.