What was your other game, Everquest 1? How can you prove that any game except the same game is even comparable?
How about this?

Same PC, same MMO, same connection, same player, same dungeon, same boss move.

Situation 1: I was not casting anything. Plumes/Landslide appears under me. I move out of it. Nothing happens, I do not get hit.
Situation 2: I was casting a spell with a cast time, probably Adloquium on tank or Succor. Plumes/Landslide appears under me. I interrupt my cast by moving. Cast completes anyway because it was nearly there. I'm out of circle by the time boss cast is over. I do get hit, and possibly die.