I know complaining about downvote is not the right thing, but the above is someone else's comment, not mine. Why was it downvoted (I see it grayed) ? It's an us

I know complaining about downvote is not the right thing, but the above is someone else's comment, not mine. Why was it downvoted (I see it grayed) ? It's an useful information without zealotry or "we-know-betterism".