Can you provide some example from the 80s and 90s? I'm not saying you're wrong but none come to mind for me.
Just thinking about the 80s with Marvel there were the two secret wars and contest of champions but none of them went extra issues. Dc had Crisis and Legends and millennium.
I didn't really collect any events in the 90s that I can recall. Zero Hour comes to mind but that didn't go over.
It seems to me to be a recent thing. Fear itself, invasion, house of m, civil war, world war hulk.... None of those went over.
Again, I could be wrong. I'd like to hear further input.