You can totally get to this by removing the `is:issue` or `is:pr` from the search field. That'll show everything, regardless of type.

IME, it's very common for people to open an issue and immediately or soon after open a separate PR for the issue, so you end up with lots of duplicates (or more if the original PR is abandoned and new ones are created, or there are competing PRs for an issue). Having both PR and issues in the issues list just made it unwieldy.

I confess that I have occasionally gotten this mixed up, i.e. see a pull request in the issues list, confused it for an issue, and "fixed" it by implementing the same thing that the pull request did.