(For the purposes of this comment I'm mostly referring to Atom/
1. RSS is, at the end of the day, a syndication format, _not_ a feedback or posting format.
2. RSS feeds have no real concept of portability between devices or user agents. Kludges like OPML can be used to aggregate feeds for sharing across user agents, but they still don't actually store device-specific metadata that a user would like.
3. If RSS feeds contain both the article and the content, then there's both little incentive for the user to actually visit the site and no analytics for the author to understand which articles are popular. When authors put summaries in their feeds with links to the original article, they degrade the experience for the reader.
Services like Wallabag which scrape and store article contents for later viewing seems, IMO, more Lin line with what users want while being fairly seamless for the author. There's also technologies like WebMentions for server owners to comment on other blogs or things like Usenet to freely discuss articles.