More importantly, it needs to draw contributors from outside the Anglosphere to work on languages other than English.
English wikipedia has 3.7 million articles. Spanish has only 810,000, Chinese just 300,000-ish, and Hindi less than one hundred thousand. That's the top four most spoken languages in the world right there.
For Hindi in particular, there's a big competition-with-English issue. There was a study at some point that Wikimedia commissioned that found that most educated Hindi-speakers preferred to read and contribute to the English Wikipedia. IIRC, one of the reasons was that they felt it promoted Indian culture to a more international audience if they wrote an article about an Indian location, or novel, or historical figure, in English. Another reason is that a lot of higher education in India is in English already.
(Also, anecdotally, the South Indians I know would rather use English than Hindi; their own native-language Wikipedias, like Kannada, are too small for them to consider them viable, and they see English as more "neutral" than Hindi in domestic political terms.)
English wikipedia has 3.7 million articles. Spanish has only 810,000, Chinese just 300,000-ish, and Hindi less than one hundred thousand. That's the top four most spoken languages in the world right there.