I think because lots of "teenagers" are "emo's" according to the movie directors, thus, perfectly suitable to being killed.
Just think about, you say emo, they think "teenagers".
And emo's is a lable (stereotype) for people who are known for cutting themselfs and killing themselfs for the most stupidest reasons, such stories (weither fake or not), could inspire movie directors into killing them anyways, coz "if teenagers are emo, and want to be dead, and feel horrible, but are slaughtered by some maniac with a spoon, then isn't that awesome?".
I might think into the wrong direction tho