And of course it's on someone's personal blog:

One of the more inane lines of criticism levelled at Joker is that it doesn’t have a clear message and is therefore irresponsible, as though film should be primarily a didactic medium signposting rights and wrongs in the least ambiguous way possible. It’s been 128 years since Oscar Wilde wrote that, “There is no such thing as a moral or an immoral book. Books are well written, or badly written. That is all.” Our critics have yet to catch up with Wilde’s vision of art and they resemble the moralists of Victorian times more and more with each passing year. But, on the other hand, surely a film based on a comic book character might be expected to come with a clear sense of right and wrong? A lot of the negativity expressed towards Joker seems to stem from a feeling that it is trying to be something that it is not, that it is above itself. At the most banal level, we can note that it is a serious film masquerading as a supervillain movie. This causes some discomfort as people are mistrustful of masks. (“Man is least himself when he talks in his own person. Give him a mask, and he will tell you the truth.”) Why is there ambiguity when there should be clarity?