Good documentation is a consequence of a large community.
Because if the community is small you don’t know if the documentation is good. Good documentation is not only “complete” but reachable and understandable.
But if the community is large, the community will demand tools, documentation, and solutions
Another aspect to consider is how open is that community. If that community pay a lot for their products, there will be a community that would not want to share their knowledge. In open source communities, people are more able to share knowledge