I am currently subscribed to 303 feeds, and I pay for a service (Feedbin) that makes sure I can accessed them all online and sync them with a reader application (Reeder for Mac). I would be waisting time that I should be spending just reading if I had to visit all these sites by myself: whether I had bookmarks or a memory.
But there will always be a threshold somewhere. My brother and I are both huge fans of continuous comics online (I am currently enamoured by Go Get a Roomie!) and I depend completely on my feeds while he has no problem going by memory (knowing when comics usually update) and bookmarks. The difference? I am subscribed to 73 different online comics through RSS.
My mom is slowly learning to use RSS as well. Although she keeps swearing by Microsoft Outlook and it took some time to figure out how to add feeds there. I have been encouraging her to get into it. What is it used for? Currently with press releases issues by different monarchies. Sure there are journalists that report on this and it will eventually trickle down onto her Facebook wall, but this way she can stay on top of the latest news without having to check a website on a daily basis that only updates sporadically.