I think most people don't see the value in RSS feeds because they are used to the business of forums and social networks - where you don't need (or have the capability to) process _all_ the information.

RSS feeds are perfectly suitable for stuff like blogs, podcasts, webcomics, etc.pp. - not for platforms where a new item pops up every few seconds.

For podcasts people use a separate app like PodcastAddict or iTunes - for webcomics and blogs the author(s) usually also have twitter to announce a new item or an entirely separate platform like DeviantArt or WebToons.

So RSS is indeed not required to keep track of new submissions. I actually have a colleague who isn't using RSS feeds and instead keeps bookmarks and checks each page individually (given he only keeps track of maybe ~30 pages).

In conclusion - I think they don't see a value in RSS feeds because the existing options they're using already fulfill their needs.