There are other factors at play at Wikipedia too. In my native language, Danish, Wikipedia is all but dead. Years ago, I tried contributing within my own field. I researched and spent hours adding relevant information to different topics, only to find out a few days after that all my contributions had been deleted by the administrators.
Here is the Danish site for one of the most beloved Danes: https://da.wikipedia.org/wiki/Michael_Laudrup
Here is the English: https://en.wikipedia.org/wiki/Michael_Laudrup
It's just one example, but it is true for culture, history and many other areas. If you want to know anything on Danish matters, the English Wikipedia is usually a much better option than the Danish.
Lower English language fluency in the general population, compared to the Netherlands or Scandinavia, supports this of course. But also the fact that German remains a scholarly language to this day (in the humanities but also in some branches of engineering).