I can see arguments for and against; it’s certainly not black and white.

But here’s the main thing as far as I’m concerned. Designing in the browser locks you very quickly into technical realities, so right from the off you’re constraining the possibilities. Yes constraints are indeed a good thing within design per se, but when you’re trying to make new things, working within the limitations of what’s technically possible now just limits my imagination too much.

There’s always ways to make things work. For me it’s starting out with a big idea, no matter how detached from reality and then working out how the hell to make it work. Personally designing in the browser right from the off can sometimes be too limiting.

But then I guess I’m not a big fan of reality anyway.