Why do people hate each other because of their taste in music and style?

People are so insane on here. Why do you guys hate each other or other bands (for example emos, MCR, FOB) so much. Its not even that necessary. Everytime I'm on here, every other question and answer is the same. "why do FOB sucks" or "I hate MCR they suck." For me I like My Chemical Romance and Fall Out Boy and I like some metal bands, indie and a lot of different types of music in general. Its not helpful or healthy to keep bashing bands and people all the time.