It's bad because it tells the truth.
The real villain in the Joker movie is the society that created him.
Blue-pilled simps hate the movie because it makes them look bad and makes people sympathize with mentally ill loners. Blue pilled cucks love to say that Incels are the only ones at fault and cannot be victims. This movie allows people to see what the descent into madness is like from a mentally ill loner's perspective. It allows people to sympathize with someone and actually understand how it would happen.
He's simply responding to the bullying and ostracization from society. Soy cucks love to say that Incels are 100% at fault for all of their downfalls and gripes in life when in reality, we're the actual victims.