Except some mobile users prefer desktop site versions, and zooming every time you wish to quote someone would be annoying. The rating buttons are already too small to push without zooming on mobile.
I sometimes use desktop versions on mobile when I find that the mobile version breaks my preferences more (such as relocating userbits to tops of posts which I find rather disruptive to reading posts, or using font sizes that, ironically, are too
big for my cell screen).
I don't think the rating buttons appear too small to hit? They're about the same size as the formatting buttons of the reply box, and the latter I've not had issues with. My cell phone is Samsung Galaxy S II, so it's screen isn't humongous.
(If anything, editing out a single character requires much more accuracy than hitting a button of that approximate size.)