One of the major GitHub social contributions to the community is the ease of forking. I don't mean as part of a "contribution workflow", but as a tool for getting an upstream team to change their attitude. A famous case was Node.js and how it ended well (merged again - http://anandmanisankar.com/posts/nodejs-iojs-why-the-fork/) but was a smack of sorts for the maintaining company. There are others, too. I'm talking folks that elicit changes in maintainer policy.
Generally, any viable F/OSS thing is going to end up on GitHub if it fits (Git has size limits; GitHub have a page on limits - https://help.github.com/en/articles/what-is-my-disk-quota). It is going to exist there with Pull-Requests and Issues enabled by some group. If a team that "owns" a compelling F/OSS thing on GitHub and attempt to not have Pull-Requests or GH issues - the thing effectively gets taken away from them in a fork, that has that turned on. Sure, they may insist the other "team" doesn't use their trademarks, but they used and OSI approved license so that's all they can do. The only defense against that is to NOT have a compelling viable project. Well that's not absolutely true - https://github.com/mackyle/sqlite is a fork of something that's canonical on Fossil but https://github.com/mackyle/sqlite/network shows there's no maintained-divergence on GH. SqLite is super viable as a project though - things are happening to it at enough of a pace (2 or 3 commits a day) to make you overcome objections to contribute at the source in Fossil if you want to get something into upstream. Maybe after you tried to build it from a git-clone (assuming up to date) and prove your patch there. However if D Richard Hipp went on a 6mo vacation, Sqlite would have relocated to GitHub without him. Forks are going to happen on GitHub regardless with PRs enabled. You might as well embrace that, and play ball by leaving PRs enabled for your repo too. Subversion's not in a shameful place if its source is in Git. Instead it is boosted, IMO. Time was when your wire protocol (at least WebDAV) was lingua franca. Now it's Gits: Perforce, PlasticSCM and Mercurial all speak Git. - Paul
