In The Office episode where Dwight "pranked" Holly into thinking that Kevin is "special", why didn't she get angry at Dwight and confront him for what he has done to her?
I don't have any references or anything, but this has always seemed reasonable to me, for the following reasons:
I think the easiest explanation is that she was much more embarrassed than she was angry. She accepted what Dwight said at face value and apparently never tried to look into it any further to make sure that was the case. As a HR rep, she should really know if one of the workers is mentally challenged. The fact that she not only didn't know that, but believed Dwight without question, is probably seen as a huge personal mistake on her part.
Based on what we see in the show, Holly doesn't seem like the type of person who would jump at blaming others if she is also responsible. In this case, she presumably had the resources to figure out that Kevin was not on a special work program. She really should have known that, especially since it was not her first day when she got upset with Angela for calling Kevin an idiot.
We can probably put a lot of the blame on Dunder Mifflin as well, for only giving Toby 1 day to train Holly; but at the end of the day, it seems in character for Holly to blame herself instead of Dwight.