The majority opinion isn't always accurate, but it is generally useful, especially in a narrow community of your choosing.

One way or another, you have to face the trade off between the expected value of the time you will lose reading the comment, and the expected value you will extract from the comment. In other words, how can you decide if a comment is worth your time or not? There are several data points that can help you make your decision:

• Overall quality of comments, that you know from prior experience with the site.
• Whether it belongs to a thread you participated in. (That's not objective, but what counts is the value the comment has to you)
• Length of the comment (the longer ones tend to be more valuable, but also takes more time to read)
• Upvotes and downvotes (highly depends on how much you trust the community there)
• The content itself doesn't count, because you need to read the comment to judge it.

Now assume your time is valuable, and you need to sort the weed from the crop. Without a voting system, you're left with the first three criteria, maybe only the first two. In the end, you are likely to read either few comments, or almost all of them. Voting systems can help you do better.

The problem is, you also have to judge the voting patterns. To what extent do you agree with the votes you see? The more you do, the more you can let the community judge for you. Enjoy your time.