Tl;dr It's mostly about "GM forgot they're not dealing with NPCs."
While players who treated the rest of the group as NPCs were pretty bad themselves, even those tended to be limited to what their PCs could affect. When its GM though the problem became a global/foundational one cause they were responsible for the world itself.
That's why I usually said, "at the end of the day, unlike the character themselves the guy across the table CAN
in the face.
"... Welp, I ain't joking here.
(A good reminder to keep oneself in check if nothing else.)
Just made sure you didn't actually deserves it when it happened.