Depends on your goal no? If your goal is to not accept random contributions or PRs, then being able to disable PRs completely, seems like the perfect approach? Up until this change (which happened almost a year ago, FWIW), it was impossible to just have a read-only mirror on GitHub that didn't get hit with drive-by PRs that just waste time, for example: https://github.com/videolan/dav1d/pulls?q=is%3Apr+state%3Acl...
I'm glad we can finally completely disable it, as it seems to just confuse people when you're not actually accepting PRs.