We subscribe to feeds because we find what that person writes interesting. If the feed is by several people, it is less successful. I don't think I've subscribed to any multi-author blogs.

But even a single-author blog is too general. We're interested in what the person has to say on one subject but not others. Many blogs are single-author, single-subject, but even that may be a bit too general. We're only interested in what they have to say on a single product, a single idea, a single issue or individual.

The perfect feed would filter by author and idea. Joe Smith + Kensington Expert Mouse. Or many-to-many: [Joe Smith + Dale Jones + Jane Doe] + [Kensington Expert Mouse + Manga + RSI]. Perhaps this is what RollYo does? I'll need to check that out.

Since we cannot find a person exactly like ourselves, we fashion one out of the bits and pieces of the shared interests of many.