+1 on this. I have never done mobile-first designs. I think they are mainly popular due to frameworks and it’s easier to start from bottom up for the mass populus. Probably a few other reasons but nothing that makes desktop-down a disadvantage.
I disagree that it’s supposedly more code to do desktop-down. It’s simply backwards. Heck - fluid design incorporated you can actually probably do it in less code. Probably just depends on your planning and your general skill. I see so many people fling 20 media queries at a page…why?! Poor architecture.