I have heard George Bush did the same thing with emails, but it's not even talked about.
Honestly, it's just a convenient "reason" for people to dislike her. It's very, very clear people make all the important judgments within 0.1 seconds of looking at a candidate, and any facts presented after that are simply adjusted to fit their view.
"Trump has sexually assaulted many women, Trump bought 100s of thousands worth of supplies from small businesses and just didn't pay" -> He is good at business, and the women are just lying for attention
"Hilary Clinton kept emails on her private server, which technically broke a law, but others have done the same" -> hilary for prison!!
"She is corrupt" is thrown around over and over, however the facts don't support this, or at least suggest she is no more corrupt than any other politician, but people say it enough and it becomes a "fact" of its own.
Trump may actually go to prison for assaulting a young girl, but people either don't know or choose to conveniently forget.
It's the same as "that lady definitely killed her child and pretended it was a dingo, look she isn't crying she is a monster".
People are quite simply really, really stupid unless they go out of there way to question their biases.