The other problem is that the worst offenders are the ones least likely to respond to getting or seeing this sort of nudge, so there is some adverse selection g

The other problem is that the worst offenders are the ones least likely to respond to getting or seeing this sort of nudge, so there is some adverse selection going on. It's probably self correcting over the long term, but meanwhile we lose the sort of links that would (or rather, might) enrich the conversation through overcorrection by posters. It's the obverse side of the slippery slope, I guess.