I don't understand why anyone expects RSS, the transport and encoding format, to contain filters, recommendations, and social aspects. Where do you think all t

I don't understand why anyone expects RSS, the transport and encoding format, to contain filters, recommendations, and social aspects. Where do you think all those people who post (shortened) links on twitter get them from? Visiting all the websites by hand? How many of them are retweeted without actual having visited the site and read/consumed the content? Can sub-140 characters contain enough information to allow the next level of filtering, social or otherwise, to be really effective?