My mother doesn't know what that is or its use. Neither does my brother, sister, neighbor, dog, ipad, etc. So I'd say only geeks know what a feed is. Then let geeks use an extension and don't bother +90% of internet users with that.
It is in a sense like developer tools, if you know where they are you can easily activate them and use them, if not, they are out of the way.
While it's probably true that geeks make up most RSS users, that doesn't mean either that it should be this way, or that it will remain this way, or that there is some obvious and immutable reason that it must be this way.
In fact, of course, using an RSS feed is a very simple concept, which turns out to be extraordinarily useful to normal, non-geekly folks who just want to read a lot without being pestered by all the normal encumbrances of the web.
While I agree that feeds are a simple concept, the vast majority doesn't care. Feeds have been available since the early 00s and its adoption hasn't grown outside the geek circles. People just don't like to be bothered with the simplest complexity.
I bet less than 80% of ordinary people even use bookmarks, being way simpler than feeds in concept.
Now in the good spirit of a designer in search of a solution to everything and everybody, add an option in preferences to show/hide the feed button. How about that?
The preferences in Firefox are already cluttered. Using about:config seems appropriate.
Edit: Some are claiming that you can still add the button to the toolbar, it’s just off by default. That sounds extremely reasonable and confuses me at the same time because I don’t understand what all the fuss is about.
It is in a sense like developer tools, if you know where they are you can easily activate them and use them, if not, they are out of the way.
Good riddance.