Unbiased, or even slightly biased, is impossible. The torrent of factual information is of such a magnitude that it is impossible to present “all the facts”. And presenting any subset of those facts, even a random sampling, induces a bias in the resulting narrative. Including the information suggested in the article would add a different kind of bias. Impartiality is impossible. Neutrality is a a lie. Strong bias is inevitable, no matter the intent.
That's a red herring. The point of the article is that Wikipedia is badly biased in areas relating to leftist ideology. Wikipedia is a good source for technical information, but once you try to use it for historical, political, or religious research, you're going to end up uninformed.
>badly biased in areas relating to leftist ideology
Leftists could and do stay say that your opinions about their ideology are right-wing biased. What makes your statement more accurate than their position?