Well not everyone is coding in terminal windows and doing console-only stuff... for me doing interactive 3D development, a high res screen (or a couple of them) and a powerful machine is of equal if not higher importance than my keyboard.
I generally develop in terminal windows, doing console-only stuff, and I still feel stifled if I don't have at least two displays. I know that all the cool kids are using split terminals and the like, but I like to keep log output visible, a browser in a separate space and a console debugger up without having to toggle between them.
That anybody can get anything done with such constraints is amazing to me, but he's obviously quite good at it.
I use to feel this way as well, until, nearing the end of university (read: I was rather broke), I had the perfect storm of computer hardware disaster. I was forced to use for about a year just a single netbook with less than impressive resolution. Tmux and tiling window managers became my friends out of necessity.
Cut to a few years later and now I have 3 high resolution screens in front of me, pretty much all the time. I still tend to use just my laptop screen with tmux though, with the rare exception (during deployments, mostly).
I won't say that a single small screen is better, but I do think from personal experience that, after some time and initial effort, it really is not the handicap people think it would be. It certainly won't slow you down like a thumb keyboard will.
Haha. Same progression for me, too. Towards the end of uni, my Windows rig completely broke down.
Being broke, I ended up with a Toshiba netbook that couldn't handle more than a few browser tabs at once. Installed Debian to squeeze out some performance over Windows XP (first foray into Linux). Best thing that ever happened to me.
Soon I learned vim, tmux, and had my entire dev environment in a Guake terminal overlay that I could quickly toggle in and out of view. It was like having two full screens in one.
My work just bought us monitors and everyone is dual/tri-screening it. I just dock my laptop and use the single monitor, still using the same guake/tmux/vim setup.