This idea is quite similar to what Bluesky is doing, with "Labels" https://docs.bsky.app/docs/advanced-guides/moderation.
We'd need some way to crowdsource the verification and validity of the labels so people can't just put low-quality or abusive labels everywhere.
It could potentially reduce the amount of work moderators need to do because spam would be labelled as such by anyone and if a few others also label it the same then it would reach a threshold where the label becomes active.
Does anyone have experience with this way of moderating content on Bluesky? How well does it work in practice?
So, a failure even on their own terms.