GitHub provides a lot more than the open source tools. Primarily it provides community. Most people would rather not have patches received by email. They would prefer a web-based interface where you can comment, adjust, and accept.
This is a classic case of not getting it.
You can manage your repo independently and push to GitHub when required. It's not even hard. If, as an open-source developer, you want me to log into your own personal bug-tracking system, your own personal source-control system, you've lost me as a contributor.