>Because DuckDuckGo's index of the yarn's website could be screwed or out of date.

And why should we know about DDG's index info about Yarn?

Just visit Yarn's actual project site (which is what you're supposed to be criticizing), and focus your critique on what's actually there now.

>Also, because people communicate using language, not axioms.

So? How does that justify adding off-topic/redundant information on one's critique?