My personal opinion on "EMO' guys.
I guess the reason why they self mutilating is to seek attention. They want others to know their existence.
It's very sad knowing that someone exist but treated as not existed. Human beings are social creatures and there are some minimum level of interaction to survive. When one don't get the care/love/etc they needed, they'll turn to self-mutilation for attention.
'EMO' guys don't just self-mutilate, they also influence their peers. Because of some reasons, their peer also mimic the action of self-mutilation. Some my think it's fun, but it's not.
To my knowledge, I feel that 'EMO' is a psychological condition which needed to be treated as early signs are detected. It could maim a person's life is this 'EMO' feeling is bottled up for too long.
There's up and down in life, and I feel that being in the state of 'EMO' is the extreme downside of one's life.
I feel that they shouldn't be discriminated and deserves encouragement from their friends/media/family to seek treatment early.