[nicolaslem]

That may be one explanation, but more broadly with analog audio it is actually quite difficult NOT to end up with an AM receiver.

[jacquesm]

Hehe. That's a very good point.

Of course, if you want to build a proper AM receiver you will find that it is quite hard ;)

Same with oscillators and amplifiers. You always get the other one first.

Oh, and it is also very hard not to build a microphone. Except...

[rcxdude]

Yup, pretty much any nonlinearity will demodulate AM.