I remember a long time ago (early 80's, maybe through the early 90's) that, aside from the QB moving his head and yelling the call, or there was a clearly-defined full-line reset, there was absolutely zero motion before the snap. Period. Full-stop. Otherwise it was called a false start/illegal motion prior to the snap and they lost 5 yards. Seemed very simple.
Then at some point (maybe around late 90's, early 00's), pre-snap motion started creeping in all up and down the O-line and false start calls got really muddy, confusing and arbitrary. I guess the rules had changed considerably and I wasn't paying attention. If there was once a "no motion whatsoever" rule in the early days, they should have considered going back to that, instead of stacking even more caveats and what-if's on top of an already existing set of over-complicated rules full of loopholes.