Syncing is very important. Most people have at least a computer, a NIT, and some kind of phone (sometimes also with this function).

I have RSS feeds in screen on a server. I have RSS feeds in Opera on my laptop. I could get RSS feeds on my tablet and phone, but I bet this would make me lunatic. Because some already overlap.

If you have IMAP, it is synced. PIM (or equiv), sync is important. Bookmarks? OK, point there, but back in the days Netscape had LDAP support for this purpose. IMO this is important for RSS as well. You can have the same RSS feed on several devices, but what kind of use is it to know that some are unread when this isn't synchronized between devices? This is not a NIT problem, just a generic problem.

Another problem of RSS is signal-to-noise. Some websites solve this by using categories and allowing the user to sign up on specific categories. Or, they allow the user to specify the categories they're interested in in their profile hence they have a personalized start page. But then there is this issue of too many RSS feeds. So it has to be intelligently sorted. This isn't easy. And that is why RSS is not something to use without serious hacking on the data. I subscribe to a newsletter of a website instead of their RSS feed and get daily the news on a specific time in a nice HTML-free (chosen by me) e-mail.

A simple example of hacking the data: ignoring based on keywords in title or body. In an IM client, e-mail client, or IRC client you can do this. In an RSS reader you can't.