Perhaps offering a range of interoperable UXs would prevent it from becoming such a stark either/or choice?

This is the thing, isn't it?

Moving off github and back to "plain git" (or plain , we're still excessively using mercurial over here) seems quite a good idea for that. As Drew outlined in his article, and there's little to add I guess:

"Did you know that GitHub also captured the meaning of “pull request” from git’s own request-pull tool? git request-pull prepares an email which will ask the recipient to fetch changes from a public repository and integrate them into their own branch. This is used when a patch is insufficient - for example, when Linux subsystem maintainers want to ship a large group of changes to Torvalds for the next kernel release. Again, the original version is distributed and bazaar-like, whereas GitHub’s is centralized and makes you stay on their platform."