That's a big problem. By the verbal standard that Nancy used for banning advancedatheist, I and lots of people here are in danger of being banned. I just argued on SSC that it could be preferable for a country to limit how many refugees it takes in when they are fleeing the Holocaust, thus leaving the remaining ones to die horribly (if the country has taken in as many refugees as it can accommodate, this becomes a case of torture versus dust specks).
Of course, that would extend to banning people for supporting standard torture versus dust specks too.
It's an important part of rational discussion that we be able to say things that pattern-match to promoting horrible ideas.
There should be a difference between people who post the same controversial opinions over and over again like a broken record and people who write about a wide variety of topics and sometimes post controversial things, e.g. people like you. The latter should be allowed much more and they should not be banned even for the most extreme opinions, because they have a controversial idea because that's where their reasoning led them to, and not because they simply want to promote their popular pet idea here.
I've gotten sufficient evidence from support that voiceofra has been doing retributive downvoting. I've banned them without prior notice because I'm not giving them more chances to downvote.
I'm thinking of something like not letting anyone give more than 5 downvotes/week for content which is more than a month old. The numbers and the time period are tentative-- this isn't my ideal rule. This is probably technically possible. However, my impression is that highly specific rules like that are an invitation to gaming the rules.
I would rather just make spiteful down-voting impossible (or maybe make it expensive) rather than trying to find out who's doing it. Admittedly, putting up barriers to downvoting for past comments doesn't solve the problem of people who down-vote everything, but at least people who downvote current material are easier to notice.
Any thoughts about technical solutions to excessive down-voting of past material?