Really!? Can I ask why? Why not just make the browser about 1050px or so wide, you can view every website out there and you can have other things in the extra space (twitter, client, terminal, downloads, whatever).
I do this too. My screen is pretty much always taken up either by a full-width Emacs, or a full-width Firefox.
I can't speak for diN0bot of course, but the reason I work this way is to minimize distractions. I don't want all that stuff in my peripheral vision when I'm busy trying to get stuff done.
Assuming you're using a Mac, opt-cmd-h will hide all windows but the one you're using...
Personally, what I find worse than 'distractions' is being blinded by whitespace caused by Firefox (/whatever) being way too huge.
And, full-width emacs!? On my monitor (with a rather large font size) that's almost 250 columns, I hope you don't have any code over there! If you're vertically splitting emacs, then, I think we're on the same page. It's not about windows themselves being any specific size, it's about making them an appropriate size for their content.
my husband is not a developer or tech-savy and he runs ff partial width of 17in macbook. (75% i'd guess?)
as for the feedback button on the side of pages: it annoys me. whatever. a good product has users that really hate it and really love it.