And I now see that contrary to the feature request, it's only asking for 5 karma for immediate descendants, not anywhere in the chain, so I shall go now and ask that to be updated.

Can you explain what this would accomplish at all? I'm not seeing anything that it accomplishes. If anything, it actively makes the problem of good threads that happen to have been started in a negatively downvoted comment worse. Moreover, it would lead to the situation where people are replying to a long-thread and then get a karma hit because it happens that way back up in the thread the initial bit got downvoted. That means that among other things, replying to threads where one is looking at single post or with a permalink becomes essentially a karma trap. This accomplishes nothing. The primary problem with trolling is that it clogs up the recent comments sections. High quality comments downthread of a bad comment don't have this problem. This seems like an even worse idea than the already implemented change by such an order of magntude that part of me is wondering if this is a deliberate use of the Dark Arts to make the current change more palatable in comparison.