Why Do People Hate One Direction?

[How Are You?]

I'm not a "directioner" but my sister is and I understand if you don't like their music, everyone has different tastes, but none of them have ever given anyone a reason to hate them. My mom forced me to take my little sister to a 1D concert last year for her birthday, I met them, and they're actually extremely nice guys. The hate they get on social media is pretty harsh. It's okay to state your opinion if you don't think they're good singers, but why are people so mean about it? And it's not just them, it's all "teen idols". In my opinion 90% of teen stars nowadays don't have REAL talent, but nobody deserves to get death threats or to be hated so much at such a young age.
I don't like their music, but they're nice people.