I didn't say she was unqualified. Diversity hiring usually takes the form of recruiters making special efforts to find candidates from underrepresented groups or "unconventional backgrounds". This can raise a candidate's visibility where they would otherwise be lumped in with everyone else.
Things I did not say:
She is unqualified. I haven't interviewed her, so I have no idea how skilled she is.
She was a diversity hire. She might have been. She might not have been. But it that company has a diversity program, it probably increased her chances.
Diversity hires are a bad thing. I don't really have a strong opinion on them, but I'm sure there are pros and cons for both companies and candidates.