>but why is he near universally regarded as more skilled?

But to be fair, Outkast may be the most balanced hiphop duo of all time. I don't think Dre is galaxies apart from Big Boi in lyrical skill as some people do, I think they are very very close in talent, with Dre getting the slight edge. But Outkast and De La are the closest duo in talent level in hiphop I think.