I think it's network effects from it's founder as well. It is written in Python, Chad is active with python stuff. I think that the Python community is generous, but I doubt any more so than most other OSS communities. (Please prove me right!).
Speaking for direct personal experience: the Python community is amazingly generous. In some ways, more generous and giving and understandable than any other community I've been part of.
Of course, I'm grossly biased[1], and have been very lucky[2]
