I think there are definite categories. They seem to range from legitimate uses of downvoting such as against obvious trolls, facetious argumentation, etc. to enforcement of ideological tyranny. It's always interesting to analyze.
Well sure, describing downvote patterns as weird doesn't mean that the majority of downvotes are bizarre. The bulk are completely comprehensible. But I can't think of anywhere else where I see as many completely reasonable comments heavily downvoted for incomprehensible reasons.
