The complexity of stereo is way above my pay grade. A hammer has too many moving parts for me.

FWIW: i don't remember the last time i "played a PA" that was mono! all the systems i use or have played through are stereo --- that way for years, IME.Has anyone played a PA that isn't mono?
well, you found out before i did!WHAT?!! Everyone is going to stereo?! Why the heck am I always the last one to find out?!
per the OP: i have heard of no 'movement' toward "stereo" --- i think it's the case that a lot of players refer to their version of bi-amping as "stereo."