Most of the "Illumiwhati" felt like fluff, fan service cameos that didn't really amount to anything substantial by the time they were killed off, so I can definitely see where she's coming from. No Way Home dropped five months before this and did a way better job at interweaving their surprise cameos into the story in a meaningful way by the end.
Hayley also isn't the only actor to be frustrated with this movie. The main star, Benedict Cumberbatch, had his issues with the way this flick turned out as well as Elizabeth Olsen...which kinda says a lot, lol.