Perhaps he is not a web oriented professional, or he does not give a shit about the rest of the world and ignores everything outside the anglobubble.

Why would anyone be aware of Yandex unless they live in Russia? Even here, I mostly use Google.

I'm personally aware of Yandex because they have one of the most aggressive search crawlers on the entire internet, judging from our Apache logs.

Well, very few members of HN community actually uses Sina Weibo, but we're aware of it, aren't we?