> or better yet, have aggregators like HN add a badge if it's likely AI generated

How could you possibly tell? I've been playing around with AI detectors, putting in known all-human samples, known all-AI samples, and mixed samples.

The only thing it's gotten right is not marking a human sample as 100% AI (but it marked one of the AI samples as 100% human).

Having such a mark would be a witch-hunt for sure.