Responding to Dan Lockton:
Not all feeds are designed to spread the article-length content of blogs.
One of my own feeds, for example, will at first glance resemble a partial feed.
On closer examination, my feed turns out to be linking to longer posts from other sites. This sort of blog - sometimes called a link blog or a summary blog - is actually older in pedigree than the more modern blog, and in fact more resembles the original use of RSS - to provide content for what are now called webtops.
You couldn't fit a whole article on a webtop, and that would really defeat the purpose. The whole idea of a summary (as in 'Rich Site Summary') is to provide enough info to make a choice.
Now of course there are commercial sites that use summaries simply to drive traffic. They also use links to drive traffic - that doesn't make links bad. What needs to be examined is not the practice but the intent. If the intent is to provide a certain type of service - as mine is - then that should validate the technique.
Indeed, while I've pretty much reconciled myself to the current state of blogging, it has always bothered me that the RSS produced by blogging engines - every last one of them - produces 'link' elements that point back to the original site, instead of to some third party topic of discussion.
This virtually by itself ensured that blog publishing would be primarily egoist, which links to other sites something that would take extra effort and additional encoding, making it much less prevalent than would have otherwise been the case.
Imagine what the web would have looked had the default in blog posts and RSS feeds been as it was originally used, to point to someone else's site. Imagine the conversations and linkages that would have produced.
Instead, the current system focuses on browsing RSS by source rather than by interest, with sites like my own the exception rather than the rule, and so the merging of content and ideas that could have happened has progressed at a much slower pace than it would have otherwise.