I would also mention Wikipedia. I remember reading in 2015 that the number of editors has declined and if I remember correctly, the situation has got worse. It's a perhaps the greatest example of a international non-profit platform for sharing knowledge.
If anyone has ideas how to go around that I would be happy to hear. For example, if there's list of articles to be written I can volunteer to help write about them. I have written few articles to Wikipedia and can also help with the technicalities of adding content there. It's very easy .