Because a lot of people I know are purest indie/scene kids who can't understand how someone can listen to Asking Alexandria and Pavement. It's one or the other, everybody has to fit a stereotype or group since you're weird if you don't. It makes it easier for them to judge you. Then of course there's the jock types who like the Billboard/chart music and naturally hate anything guitar related. As for the acoustic/folk stuff, most people go for the classic "it all sounds the same".