My post was a rebuttal to onmouse's insinuation that MooTools didn't already have a mature, fast, & functioning CSS selector. Valerio's post quite clearly stat

My post was a rebuttal to onmouse's insinuation that MooTools didn't already have a mature, fast, & functioning CSS selector. Valerio's post quite clearly stated that, at the time, there wasn't a measurable performance improvement. Regardless of his misunderstandings about the contribution process, he wasn't ready to trade his team's control and design philosophy for dubious performance gains. That seems perfectly reasonable to me.