"After an in-depth review, we’ve identified a number of open issues that have become outdated over time—some for several years."
Sounds fair enough to me.
If they were all truly outdated, then sure.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.
"Leave them until they're outdated" isn't a valid way to deal with issues in my book.
Plenty of large projects need to go through and do a bit of a sweep of old issues every few years. If your projects have the discipline to never need that I congratulate you.
Clutter accumulates in any bug tracker.
Ideally they'd've been cleaning it out more regularly and these feature requests would've been marked "not currently on the roadmap" and closed much sooner.
But I don't think I've ever seen a team do a perfect job of that, and I'm probably worse at it than they are.
But "Don't sweat over any little issue, especially if they have gone multiple years without major complaints from a sizeable part of your user base" is.