If your message depends on more information than one chunk can offer, a blurb is a response cue because it can entice the reader to go deeper into the site. That's because Web readers like to know where they're going before they click through. Sure, you explain some of your local terms if outsiders will be completely baffled otherwise, but you don't have to provide an online dictionary of English as it's spoken in Jersey City or Sydney. This isn't easy. Whatever you do, be consistent.
Modern media do the same thing, and the Web is no exception.
It's a jolt-delivery system, and many Web writers will try to pack as many jolts into a site as they can manage. Simple, clear writing is a jolt in itself, especially if you find it on a government site. Finding an honest expression of some person's point of view can be a jolt as well. But they really are different media, and deserve to be judged by different criteria. The World Wide Web inspires us to think and express ourselves in new ways.