I don't think Eric Johnson started it but it sounds like he either created or perpetuated the myth. I'd never heard about that before but I'm not an EJ fan. I've seen clips of Hendrix playing with no back plate. To me, the reasons for not putting the back plate back on are simple. For a gigging musician, convenience for new strings and set up/tweaks. Why waste time removing those 6 little screws every time? Not to mention, remove them and put them back 20 times and the screw holes are stripped out anyways, you can't put it back on if you wanted to..