Why do people hate YoonA so much?

She is a innocent and nice person.Honestly she doesn't get much face time.What about Jessica she always gets face time too.She almost always has a line.YoonA doesn't get very many lines.She can sing but i wish SM would train her a little more.HyoYeon almost always gets dance time like solos.People say she got surgery.Why can't people leave YoonA alone and other So Nyuh Shi Dae members alone?