I have to disagree. At least on some level, NH and SasuSaku fans believe there is manga evidence to support their pairing. They have a different perspective then us, and in that perspective, their pairing has or had a chance to become canon.
In fact there are several complaints of how the anime caters too much to NaruSaku, and when they are catered to, a large percentage seem to be unexpectedly surprised, and then let themselves fully enjoy it as we enjoy our fan service. You will see quotes of "Oh I'm glad the anime knows Sakura/Hinata loves Sasuke/Naruto" much like posts above me are doing, and that's normal considering how we all want the best outcome for our ships and believing that there is a major business backing your beliefs is a nice "I was right all along" feeling.
I don't really know where you'd get a large amount of the crazy fans your describing outside of youtube.com Besides that, there are a few bad apples in every fandom.