Well, when is the last time you (or anyone else) ever submitted a patch through GitHub? Answer: never. Check out the lengths the Git project itself has to go through to work around the busted GitHub-style pull request mechanism GitHub invented.
Well, that seems to me to be because they provided an alternative to patches that works a lot better for me and the projects I contribute to, and I can't blame them for it.
GitHub's secret sauce was to use dark patterns meant to accelerate the network effect working in their favor.
Specifically:
1. Quietly kill patches as the main currency in open source
2. Redefine "pull request" to mean "the thing that happens when you click a certain button on github.com"
The end result is that collaborating with GitHub-hosted projects is made arbitrarily difficult unless you're also hosting your work on GitHub.