Why aren't RSS readers smarter???

The blogosphere (both readers and writers) can be roughly split into two groups:

• Those who believe bloggers must have an agenda and stick to it. These people believe that a blogger know to be "technical" shouldn't throw too many stuff about his private life at his readers, political views, etc. Some bloggers take it to the extreme and manage several blogs, each on a different subject (or various RSS feeds).
• Those who believe bloggers should feel free to write whatever they feel like, and it's up to the readers to choose which post to read and which to skip. I'm in this group...

Well, it's fairly easy to merge these two groups. The only thing needed is some smart RSS reader, where you could define "rules" either per blog or general, which describe the content you are interested in and/or the content you don't even want to see. So if people reading my blog don't want to read my soup recipes, they can add a negative rule to my RSS feed and still enjoy (I hope) the rest of my posts. Alternatively, people who are only interested in stuff I write about search engines, could add a strongly positive rule, which will disregard the other posts. Of course, it would work better with blogs that are better organize than mine and also include tags...

As a side-note, this is a good example of applications that can be made much smarter than they are, but people just don't think hard enough how this could be done. Technically, it's no biggy. The only problem is to think about it. I think in many cases, the problem is that people designing the required features either don't understand software well enough, to see the wealth of possibilities, or are too strongly connected to the way developers think, and don't see what would really help the "simple" users.