I think the number of world-first kills that didnt have some sort of weird stacking or left some classes out can be counted on one hand. Often they take wichever members they got and just go. I remember a massive spriest stack in a totc fight. Or Shaman stack when Heroism/bloodlust was a group buff.
Im just pleasently surprised that Dark Sim actually has some uses now, either then being a virtual wasted slot in my spellbook.