Imagine you came to this site, asked a question, and got a response that simply said "You are wrong!", and nothing else. Who would want to be on a site like that?
I hope it goes without saying that it's in all our interest to grow JLU into a larger community. What might not be so obvious is that to do so, it's not good enough to have quality answers, which I believe we have a lot of. We also need to have a community that makes both new and existing members feel welcome and supported. And that shouldn't be so hard - we're just here to learn a language, after all, and why should anyone take flak just for asking questions about it? Why would anyone even want to give anyone flak for not knowing something? When questions don't conform to site standards, we have guidelines and systems for dealing with it, making negative commentary completely unnecessary.
Unfortunately, I think there are trends of negativity on JLU. For example, there is either a person or group of people who habitually go around downvoting questions without any explanation. However, that is not what I'm addressing in this question.
I'm not going to name names because I believe in the SE ethos that it's behaviours that should be addressed, not people. But, in any case, what follows is a series of comments made recently that are not only completely unhelpful, but hostile to the goals of making JLU a place to learn. What they all share in common is that they simply tell people that what they have said is wrong, without any information that helps anyone learn or improve their Japanese:
You translated 気持ちが悪かった too literally. It does not mean what you said.
Whose translation is this?? It is very inaccurate right from the start. "(It) refers to the people you receive profit and favours from"?? That is not what the original says and that is not what the word means, either. The word just does not refer to "people", period.
There is no system for downvoting comments, and if you were a relatively new member, why would you stick around to that anyway, or see what kind of argument might ensue? If I received any responses like these when first joining, I'd have ditched this site in a heartbeat. I've been subject to this kind of comment (not one of the ones above), and it has reduced my enthusiasm for this site, because I don't want to have to deal with getting complained at just for asking something.
Update: Responses below have made the case that, if the phrasing could be made more palatable, comments that simply point out mistakes, are helpful. However, I think analyzing the comments above, or ones similar, in terms of their helpfulness might be too narrow a focus. People have options, other sites and methods for learning Japanese. If JLU is merely a place where people providing comments and answers do not feel any obligation to do so in a positive and supportive way, then the site loses, regardless of whether or not the comment is, in fact, helpful. If I could go to one site where help is framed in negativity, and one where the policy is to be supportive, I'll go to the site that is supportive. So, it's about the goals of JLU. Do we really want JLU to be known as "The place where people will tell you you're wrong"? I can't see a site like that attracting or keeping members. However, "JLU is the place where everyone is helpful and nice about it" is a site I'd be proud to be a part of and has a good chance at success.
So, my question is, what can be done to get JLU members to recognize that being positive and supportive are just as important as providing information? It seems the only way to address it is with combative comments, but I think that just leads to either arguments or entrenched defensiveness. Is there any other methodology that we have at our disposal to foster a supportive environment and weed out the unnecessarily negative commentary?