> Most bug trackers have ways to triage submissions. When a rando submits something, it has status "unconfirmed". Developers can then recategorize it, delete it, mark it as invalid, confirm that it's a real bug and mark it "confirmed", etc.

All of this is possible on GitHub issues and is in fact done by many projects, by this metric I dont see how GitHub Issues is any different than say, JIRA. In both cases, as you mentioned, someone needs to triage those issues, which would, of course, be the developers as well. Nothing gained, nothing lost.