School (I'm speaking of high school and younger) isn't the real world. Many things that are perfectly legal for adults are prohibited in school because they disrupt the mission that the school is trying to accomplish. There's certainly a grey area but things like dress and speech codes are well established and for good reasons. A service like yik-yak has no real benefit in an environment like that. In fact I don't even know why schools allow personal mobile devices at all.
As far as universities go, yes I think "if you don't like it don't go there" is much more realistic. Those students are all adults and by that age have mostly (certainly not completely) outgrown the most petty type of cliquishness and bullying that permeates the junior high and high school social scene.
That's very much not true. College students can be just as petty and cliquish and bullying as high school students.
And saying "Don't go there" isn't really a solution either. While the victim might not be there seeing it, everyone else is. They're still having their reputation damaged by the harassment brought upon them.
As far as universities go, yes I think "if you don't like it don't go there" is much more realistic. Those students are all adults and by that age have mostly (certainly not completely) outgrown the most petty type of cliquishness and bullying that permeates the junior high and high school social scene.