No, downvote cabals are worse. They are also harder to detect. Note that the distance from 1 to -4 is much less than the distance from 1 to 99.

I can easily see the point of an upvoting cabal -- you'd use it to get your stories onto the front page. And you'd only need five accounts in order to do that quite successfully.

What's the point of a downvoting cabal? To allow you to severely punish comments you don't like? Sounds petty even by internet standards. And if you do manage to get a comment down to -4, then I notice that comments in severely negative territory which aren't obviously awful tend to get rescued anyway.

See the effect of a downvoting cabal on Digg here: http://news.ycombinator.com/item?id=1579444

Upvoting a story keeps it on the front page longer. Downvoting a story makes it disappear before people can see it.