This feels like an oversight to me, and it should indeed be on the ‘All’ section of the page. An unfortunate side effect of it starting on ‘Required’ is that when you filter the results, it remains on ‘Required’ so there’s a chance you might not see what you were filtering to find.
The PR from @martin here fixes the issue, so I’m happy to go ahead and see that merged: FEATURE: Link to "All settings" for real in the admin sidebar by martin-brennan · Pull Request #35263 · discourse/discourse · GitHub
That’s something to think about, but I would like to keep the ‘All’ in there, at least for now. Because the page can be filtered to show any of the site settings, ‘All’ is still a correct label. I’m happy to reeavluate that with more feedback about it, though.