I think it's not so much a LW thing as a "one particular person on LW" thing, in which case there needn't be any particular connection with rationality or rationalism or anything else about LW apart from whatever circumstances led to us acquiring that one particular person. I expect (but have no evidence) that larger fora have occasional people doing pretty much any weird thing you might care to speculate about, including retributive downvoting. Maybe they get squashed by moderators or something. Maybe it's usually a small enough fraction of voting activity that no one cares.
Hhmm, I wonder we as a community should volunteer a set of guidelines and norms about karmic behaviour as to aid the interpretation of karma. On the other hand, perhaps an intuitive system has its own charm.
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.