I dunno, I do see some bands that I haven't heard of, but most importantly I check out bands that I don't already know, which I can do regardless of how long they've been around or whether I've already heard of them or not. I only really know 3 or 4 of the bands at HV, and I've only seen one of them live, so there's a lot of stuff that is new to me, which is all that really matters, surely? And as with all the festivals they start by announcing the bigger bands and then add the less well-known ones later on.
But yeah, fair enough if you're not really interested in the bands they have so far, although it's kind of a separate point.