Why are people so ignorant when it comes to music?

[Alex]

It seems that people nowadays, mainly teenagers hate people/dislike them based on their music taste. Also i'm a 16yr teenager and i ws speaking to this 13yr old, and he was saying that all rock music is all screaming and that they are all satanists, they want to slit their wrists and that they are all goths. I like pop punk/indie/metal/rock music and it just seems that because today is a pop genre world, that people are ignorant when it comes to rock music.
Personally i don't like they style of Justin Bieber's music, but i don't go around hating on everyone because i'm not into that. I respect Justin for getting into the music industry, and not having to go on a nationally broadcasted talent show.

I was on twitter about an hour ago and i saw this picture with arrows point to One Direction saying that if you dont like them, then you must be deaf and blind. I don't get why people do this. also when Mitch Lucker died, i saw on Facebook and Twitter that some (not all) directioners were saying that he deserved to die, just because he sang a different type of genre thann One Direction. Also when Alex Gaskarth stated his opinion on Twitter about 1D's new song, some (NOT ALL) directioners started telling him to go kill himself and that no one likes his music, and he doesnt have a right to say that.

I'm just fed up of people being so ignorant about other peoples music taste, so why are they??????