Maybe it’s a matter of scaling, but the GW2 tutorials (and several early events) have the horrible design of including bosses with AE one-shot abilities. The boss spawns, activates an attack you’ve never seen before, and 15 people are on the ground. This is not a fun introduction to the game.
Maybe they’re trying to introduce everyone to the “downed” mechanics during the tutorial. You struggle with that while the people who were not in the AE finish the tutorial event. Congratulations on your victory, hero!
Don’t assume someone five minutes into the game will recognize what is about to happen.