Actually, quite a few people thought that these states were in play. For instance, the Democrats on the ground in those states were saying that for months but Clinton and the DNC chose not to listen and provide them extra resources. Trump's team said that they were in play but Clinton and the DNC chose to ignore him and decided not to look into the matter to see if their claims were justified. Taking a look into those things could have revealed the holes in their strategies and helped them elsewhere as well, but they chose to stay within their little bubbles and not pay attention to contrary data.
But ignoring the people in the field and making decisions contrary to the evidence is why she was such a great candidate. She clearly knew better.
Yes, it's not her fault. It's the people in rural Michigan's fault for not coming up with her $500,000 speaking fee.