She's literally playing a fantasy witch who has already been played by dozens of other actresses. She's the only one out of all of the previous ones to get upset about this.
If she wants to be noticed for her face, then playing an iconic villain who has been played so many times before isn't her place to be. Fans care about elphaba, her character. She is new to the franchise and making demands of fans who have loved the character much longer than she's been in it.
Her feelings are unjustified and come off as narcissistic. I would be more open to the idea that she was being erased if she wasn't on literally every other poster for the movie. Fans made a poster that they felt more closely resembles the original poster from the franchise that was made over 20 years ago. To assume anything else is a very large stretch.
For her to react this negatively over a fan making their own version of a poster says a great deal more about her, and to me does more damage to her reputation than a poster ever could.
There are literally entire sites and databases dedicated to fan generated poster art. The entire Harry Potter series has thousands of posters that don't include the actors faces and are based off the books. Are those "erasing" the actors? Have we seen Ian mckellan go on a tirade because fans made a two towers poster that doesn't include his face? No, because it's not about them and they don't care.
If her feelings are hurt over one tiny person making a poster that doesn't include her face then that's her problem she needs to tackle herself, not dump on the people who were excited to see her play elphaba.
So yeah. I'm not accepting the victim blaming title because i don't see her as a victim. She made herself a victim in her own mind when one fan did this. You know who I see as the victim? The fan who was probably really excited to see this movie, so excited they made their own poster, and then had the Hollywood celebrity call them out publicly who now has people like you defending her for basically calling this person (who again all we know is just a super big Wicked fan) basically the devil
Literally all she had to do was nothing and it would have passed with no one noticing.