Laplace does not seem to be as evil as the stories tell, so unless she was so ditzy she caused a disaster or she changed a lot (doubt the author would make one of the protagonists be evil all along) Maxwell probably ruined her reputation and made the current society look down on women as a twisted, petty sort of vengeance for showing herself a better magical user than him.
Evil people with such pettiness is normal in these kinds of stories, and as it seems like just as Laplace, Maxwell is still alive and, despite being such a big deal already, still "proves his superiority" by fighting the winning party and staying the champion of the tournament it seems very on-brand for me... I'd bet that if anyone got close to defeating him they later secretly got a similar treatment.
...
Cue no one believing she is the real Laplace but him because, unlike her, his method to stay alive for so long slowed down his aging but he is visibly an older man when he finally shows up.