Note: While I'm replying to you, please note that I'm not claiming you've done anything like this or that you are doing these things. Rather, it's just your comment sparked these thoughts. That is all. =)
Since this topic is already fairly meta already, and because of the nature of your question, I'll chime in here as well as to why I would normally down vote your comment in other threads.
"why did people downvote this comment?"
Any discussion of voting (outside of a few exceptions such as this) gets down voted quickly. Not only is it discouraged in the guidelines, it's also generally self-correcting. I've seen far too many comments that ask why they are down voted when they clearly have more votes up than down. In addition, the conversations in reply generally revolved around why people might be voting down, and whether that is wrong.
Basically, it creates a bunch of useless commentary for no good reason.
In addition to this, asking people why they voted down a comment is annoying. The goal of commentary should be to spark either conversation or thought. If it does neither, it's really not worth my trouble to explain why I down vote it. I vote down the comment because it is a bad comment, and not worthy of worthwhile discussion.
I've voted comments up that I disagree with because the discussions they've sparked were interesting and voted down comments I agree with because they don't honestly contribute to the active discussion and exchange of ideas.
Not everyone thinks this way. I'm sure people vote up what they agree with and vote down with what they disagree with without a care to the overall discussion simply to fit an agenda. I admit I've done it in the past (I am not perfect, after all), and I've regretted it. But overall voting corrects itself, and frankly, it does not matter. Karma is representative of your value.
If you are that concerned about the karma of a comment, do not post. If people are voting down your comment and not replying, start by addressing the failings in your comment to spark proper discussion.
Blaming others (tripe like "people would rather vote down than explain where I am wrong") is weak and childish, and will get voted down without hesitation. HN should be better than that weak (non-existent?) rhetoric, and the moment you add that to a comment, you've lost.