Mixed. It's mostly people with interest in open-source. Or some people that encountered bugs, fixed them and then abandoned/forgot their github account.

That being said, we use private bitbuckets for all things internal. It's not as if people couldn't work with git. People are simply not interested in open source / github.

That said, english is a second language here, so that may explain why people are not interested in working on open source projects that are mostly made in english.