Because a downvote, with nothing else, is lazy. It doesn’t help anyone, it gives them no way to improve the question. It’s a drive-by middle finger, it tells you that someone is unhappy with your question, but with no way to tell why. You’ve said “something is wrong”, but given no useful information to fix it. Honestly, it’s the SO version of “if you loved me, you’d know.”
You say it’s “for the community”. Who? The people who already know the answer? What does it do for them?
Someone who might be having the same problem? A downvote does nothing for them, except maybe tell them this is a stupid question and don’t ask about it. Of course, there’s a high likelihood that they’ll interpret that not about the specific question wording, but about the problem as a whole. Because again, no actionable input, just a drive-by.
The only people in the community this benefits are the people at your level, who don’t care about the subject or the person with the problem, but have the time and the expertise to wank about wording and “proper” questions.
I want you to think about something: Take something you do everyday, driving, mowing the lawn, riding a bike, whatever it is. You know the basics, but you’re not an expert. You can’t rebuild a briggs & stratton, you don’t know how to calibrate a deraileur, you have no idea how to bleed brakes. Doesn’t really matter what. Just pick something.
At long last, you decide “hey, I would like to know more about this”, so you decide, “I’m going to change out the pads on my brakes.” Now, you want to get this right, because hey, brakes are important to not dying. So you do research and you work hard, but something about the process is escaping you. You go out and find the automotive repair version of SO and ask a question.
Now, you’re not an expert. You don’t know all the correct terms, you’re not even really sure what the problem is, just that it’s there, so you ask as best you can, and the ONLY response is some guy you’ve never talked to or heard of, downvoting your question, and no one bothers to answer it, because that guy has serious karma and if he downvoted it, clearly it’s a stupid question.
I want you to really think about whether or not you’d feel enouraged to finish the job, or just say “fuck those people” and get Triple A to tow your car down to Midas and just pay for it. Oh, and you’re also now fairly certain that gearheads are assholes. Because your exprience with them and their community?
You’re not downvoting for the community. You’re not downvoting for the person asking. You’re downvoting for you, because that’s easier than explaining what’s going on.
And that, my dude, is lazy.