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This post being scored so low is a good example of the problems of this vote system.
More people use Firefox than Opera so a plain simple FACTUAL comment based on Opera gets voted down by the large amount of Firefox users.
I wouldn't necessarily call that a problem with the vote system. You can set your threshold lower and still see the comments; however, the reason the comment in question was scored low (no, I haven't seen it yet), would have been because of the types of people, not the vote system. A system is only as good as its users, and if people desire to vote down valid posts, then it is not the system's fault, but the fault of the people.