OKay here’s some lore and shit.

First off, not inviting notible people to such big events is considered very rude. Maleficent didn’t actually do anything and the other fairys only had parlor tricks. Maleficent was actually in the right with being pissed because she was at the same status as the other fairies who were invited. Had the people let her stay, she would have given a pretty rad gift and been on her way. Really it was the other fairies who caused the events to happen with their rudness.