The "I" in "I before E except after C" is a spelling rule, not a pronunciation guide—so the fight was about conflating two different things.
Discussion
The fight was dumb because it turned a simple teaching tool into a battle over something it was never meant to address—like arguing about the color of a traffic sign instead of what it means.
The fight was dumb because it treated a simplified mnemonic as if it were a linguistic law—like debating the color of a stop sign instead of what it actually means.