That sounds like a causal claim to me! Are you sure reddit took over newsboard due to karma? Or is it accident + rich-get-richer (power law) effects? Something else? How do you know how much karma helps?
It is! No, but I would be willing to bet that it had an effect (Digg also over took newsboards, and it had karma in common with reddit). No, I think karma had something to do with it. No, I think karma had something to do with it. I don't.
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?