Kelly,
Basically true. However, read on to see why.
The primary function of a RSS reader is to aggregate content from multiple sources.
The idea is that it gives you one common interface to keep track of the latest happenings at sites you frequent
without actually having to visit each one. At the highest level this takes the forum of new Topic Titles for places like forums. Or it could be the Headline/Byline for a news story.
Depending on how the feed is set up by individual web sites, there can be included a small about of content. For instance, I have set the RSS feeds here to include the first 500 characters from the post.
Other sites may even include some graphic elements in their small sample of content.
The idea is not to include all the content in the feed. Rather it is just enough to let you know the overall gist so you can decide if you want to click on the link to access the full topic or news article.
It becomes a type of Dashboard that gives you a high level overview of a wide range of items. You then decide what warrants a more detailed look.
The feeds that you pull in are totally up to you. You might be surprised to learn that many of the sites you frequent provide these feeds. Of course, I have no idea which do as I do not know which they are.

Any site that displays the RSS logo provides a feed. But just because they do not does not necessarily mean they don't. Like here.
