Really? Considering Apple sold 5.5 million Macs last quarter, I'm not sure your claim that there's no growth holds water. If anything, the trend seems to be people using laptops (which are desktops) and smartphones, while tablets are stagnating. The advice to not focus on the desktop is just bad. You need to build for both.
What I said in the article was that most devs should have had time to do both, BUT if they really had to pick one, pick mobile. I'm not saying ignore desktop - I'm saying it's the #2 priority.
I would argue that it depends heavily on what is being built. Building a nice informational site with simple actions? Mobile first makes sense. Building a very complicated enterprise management tool? Your target audience is going to overwhelmingly be on laptops/desktops. yes, optimize for your audience, but that audience isn't necessarily mobile.
How well does the "mobile-first" solution work on a Nokia N95 browser? (let's not forget that not everyone visiting a webapp is doing so from latest version of Chrome, FF, Safari, Opera, etc.).
While I understand your concern, it feels misplaced given the context (Rails Rumble). Of course. Unless it is a front-end heavy hackathon, it is only natural that the business problem being solved has more weight that whether or not the site is functional on mobile.
I do agree with the general sentiment that we should consider mobile. But desktop isn't dead. (I assume you probably didn't write your submission on your phone).
