If they were all truly outdated, then sure. But as the comments have pointed out, Github also closed at least half a dozen still-relevant issues like "Commenting on unchanged lines in a pull request" that would be significant UX improvements.
That's a big one. I need to deal with perforce which has plenty not to like, but I frequently attach comments on unchanged lines in code reviews saying something like "you'll need to change this too", and their code review tool supports this.