Just one person, but I find the jira process arduous, as it forces commodity labor on the contributor. Even when the person remembers how to work with Jira patches, not everyone wants to relive that.
I suspect I'm not the only one who finds the creating and rebasing patches, lack of automated patch testing via Travis, and the less user friendly diff view just undifferentiated work. I have a couple things on my laptop I haven't gotten around to submitting solely because of this pain. I don't think avoiding github helps anything except reduce those who want to contribute.
