Vanilla 1.1.9 is a product of Lussumo. More Information: Documentation, Community Support.
This answer was flagged, and I tend to agree that the comment thread got out of hand and had turned into a discussion. I asked that it end, and redirected people here.
More generally, should we be worried about this happening in the comments? Is there anything to do about it?
I don't think we need to worry about it too much. It's certainly not something we need to request a new feature to handle. The right thing to do is to post a comment asking people to take the discussion to meta (anybody can do this). If you want, you can open a thread on meta and link to it. If the discussion continues the the comments, a moderator can lock the post; I'd be quite surprised if this has to happen more than once a month.
Not hard to enforce at all. If a user indulges in undesirable behavior after being asked not to, a moderator can suspend his account, effectively making the problem user have reputation 1 for the duration of the suspension. In particular, the user simply won't be able to comment any more.
But I don't think it will ever come to that. There have been a few blatant trolls that we've suspended, but I don't think we've ever suspended a user with more than 1 rep. Every time I've emailed a user and explained exactly what the problem is and what I'd like them to fix, I've gotten a positive response.
Here are some things to keep in mind when you see a useless/provocative/discussiony comment:
1 to 6 of 6