Upon release, a lot of people didn't like the movie (everyone recalls how Duvall was nominated for a now-withdrawn Worst Actress Razzie, but Kubrick was nominated for Worst Director as well) and when something like that happens people like to have someone specific to blame. And Kubrick and Nicholson were already icons, plus people are always quicker to blame women.

Speaking of misogyny, a lot of people laughably still begrudged Duvall making movies with a director other than Altman, as if she never should have worked with anyone else out of loyalty or gratitude or some stupid shit.

Then you have the countless differences between the book and the movie, many vis-a-vis the character, that people resented and laughably blamed her for.

Then you get to the issue that, as amazing as her performance is, it's also incredibly, deliberately weird (so is Jack's but, again, he had more credit and in any event is a man). When a woman does things unconventionally on screen, people lose their fucking minds. Skim any thread on The Dark Knight Rises on Reddit and see how long before you come across a comment from someone whose opinion about the movie begins and ends at how Marion Cotillard's body slumps when she dies. Same with Duvall running up the stairs in the Shining. It's nonsense.

Anyway, with time people (other than Stephen King lol) began to appreciate the brilliance of the movie and, by extension, the performance, and we got behind the scenes footage that showed how horribly Duvall was treated on set (e.g. https://youtu.be/8o-n6vZvqjQ?t=892) and people began to come to their senses.

But she's incredible in the movie and if there isn't a great book about her career already, someone could make a lot of money writing one.