A year and a half ago, shortly after the GNOME 45 release, I opened a pair of Pull Requests to deprecate and remove the X11 Session. A lot has happened since. The GNOME 48 release addressed all the remaining blocking issues, mainly accessibility regressions, but it was too late in the development cycle to drop...
Anyone being able to open a pull request is part of what makes a lot of design decisions shit.
More projects should normalize the culture of closing pull requests without giving a reason why. Just do it.