I remember studying electronic music at the Berklee College of Music in 1971 with the brilliant instructor Michael Rendish.
Conventional wisdom back then was that it was not possible to build a polyphonic synthesizer keyboard (i.e. able to play more than one note at a time), because of the staggering amount of signal processing required for each key.
At the time, he was right. But as we all know, today polyphonc synthesizers are everywhere, even in the toy section at Wal-Mart.
Hey! Hey! I used to have a Moog.