Because while the hipsters are great, being in the DIY punk scene for years is a whole different experience in itself. Being a street punk, crusty, or even a skinhead for years, you're exposed to a different side of society, and a good amount of your peers have been, are, or will be outlaws themselves for a time.
I'm not the most eloquent guy to write this right now (obviously) but there's a difference between just being a music fan or living by your own rules like Pure Hell, The New York Dolls, The (real early) Ramones, etc. There's no danger in being a music fan by itself. I'm not saying that everybody has to be a knucklehead, but having these outlaw party people as the ones who shaped your scene over the decades, the lifestyle is just different. I can't write today, I give up lol.