Totally agree. But this does not take away from his point that maximizing screen space is the motivation in Firefox. In fact, all you have done is demonstrate why they are driven to do so.
Maximized screen space doesn't really benefit this site.
The key element missing from this thread is that the Internet going from a text based to a multi-media (and increasingly video-centric) experience.
A lot of Internet users, at this point, do as much reading on their phone or laptop as I do reading on my TV (almost none).