[NeedMoreTea]

It's not complex enough to need extremes or great long explanations. A simple "show me" or offer to add first couple of encountered feeds to their new tabs, and perhaps a couple of popups "your XKCD feed updated! [Show]" should do it. Maybe add a notification icon to updated live bookmarks.

You know, rather less than the low level of effort put in to promoting the recently purchased Pocket.

If people can be enthusiastic about wanting auto-updating podcast apps or push notifications and auto-updating news then RSS "failed" for reasons other than capabilities or being too complex to grok.