Sure, she has very high damage to resource attacks, but she always has. What has kept her down previously was the best blitz decks were 1, just as fast due to half as much life, 2, her CC game plan of auras was very much punished by faster decks who didnt need set up time, and 3, if you went full aggro, most decks naturally pack poppers.
However, when the best 2 decks in Blitz are Oldhim and Iyslander, 2 decks prism made unplayable in CC, plus Kano being destroyed by the banning of storm striders, she is going to gain a significant meta share, cause like you said, she does have the tools to win. However, in blitz, when its a fair fight, every deck can just high roll you out of the universe. Iyslander and Oldhim set up for longer games in a very fast format, which prism just does better (but does worse against other aggro decks).
Also, Fai is not a particularly good blitz hero, Ira is still probably the best Ninja for blitz, and there are better aggro decks, there is a reason this is what the world's meta looked like. If you dont have a plan for how the game ends (or doesnt in the case of Iyslander and Oldhim) on like turn 2 or 3, your blitz deck is gonna fall to the bottom. Prism happens to be able to play both ways depending on deck construction, and this weekend's version was set to beat those top 2.