Top 5-10 what? Browsers? Because if Quirksmode is right, the fact that most mobile users of your site are iPhone users is a result of your decision only to do your mobile webdev for the iPhone, not a cause of it. As for sticking to it until someone complains - that's exactly what this article does.

But in the end, the loser is you, the web developer, because you're pushing potential visitors away from your site.