Folks seem to be waving their hands at whether there’s anything definitive written about Rita causing real harm, so...
In canon, Rita was not portrayed as explicitly on anyone’s side, and probably the worst direct consequence of anything she wrote, that was explicitly mentioned, was Hermione receiving hate mail after being accused of using love potions. relevant HP wiki article
In HPMOR, If we take Quirrell at his word in Chapter 26, Rita was trying to destroy Harry’s reputation, which is a real harm. In chapter 22, Draco thinks “The Daily Prophet was one of Father’s primary tools, he used it like a wizard’s wand.”—and we all know the sorts of things Lucius gets up to with a wizard’s wand. In chapter 80, the Prophet printed stories directly accusing Hermione of trying to kill Draco, before her trial.
I haven’t been able to find any reference that Skeeter or the Prophet were aiding Voldemort during the War, in canon or MoR.
Folks seem to be waving their hands at whether there’s anything definitive written about Rita causing real harm, so...
In canon, Rita was not portrayed as explicitly on anyone’s side, and probably the worst direct consequence of anything she wrote, that was explicitly mentioned, was Hermione receiving hate mail after being accused of using love potions. relevant HP wiki article
In HPMOR, If we take Quirrell at his word in Chapter 26, Rita was trying to destroy Harry’s reputation, which is a real harm. In chapter 22, Draco thinks “The Daily Prophet was one of Father’s primary tools, he used it like a wizard’s wand.”—and we all know the sorts of things Lucius gets up to with a wizard’s wand. In chapter 80, the Prophet printed stories directly accusing Hermione of trying to kill Draco, before her trial.
I haven’t been able to find any reference that Skeeter or the Prophet were aiding Voldemort during the War, in canon or MoR.