FF is quickly becoming an obsolete browser. iPhone uses Webkit, iPod Touch, iPad, every single Android phone (like the Nexus One and Droid), Chrome on Windows & Mac... every new Mac... the list goes on. I'm all for competition, but Webkit is clearly the champion here.
The page crahsed Safari on my iPad.
That's nice and all, but Firefox is still one of the biggest browsers out there. It's not obsolete, and you can't ignore it if you value users. In fairness, not everyone values users.
Replace "Firefox" with "IE" and your arguments are even more persuasive.
FF is hardly obsolete. The presentation used vendor-specific extensions (-webkit-) that are not part of the CSS3 spec, much less HTML5. Many of the features could have been implemented in FF had the author used -moz- alongside -webkit-.