I have been wanting to ask this same question for 110 days now, give or take a few. When I first found EL&U, I was delighted. Since then, I've been dismayed many times by the lack of courtesy, kindness, and tolerance here. I have never even entertained inviting someone to the site (I know several PhD English professors, as well as ESL and regular English teachers). They're my friends, and friends don't invite other friends to be abused.
I realize this site does have standards found in the help sections. But comments don't politely refer people to the help sections. They are often just rude. Maybe not intentionally, but still, they are. (And I'm not above bad days, or annoyance at the thousandth newbie who wants his homework handed to him on a platter. I'm no saint.)
In the words of Jeff Atwood (same thread referred to above):
Still, I think this post would be stronger with actual real world examples of snarky comments (and some data on how often it was seen, next to the examples) to show people what not to do.
(Today) When this poster asked very politely asked Does “the motor speed” mean the speed of the motor?, the first comment (upvoted) was "Can you explain why it wouldn't be okay? Do you have the same problem with "internet speed"?"
(Today) This OP was asked (in comments) for context. On providing a link, the next comment was "Don't use comments to enhance the question. Edit the question to include all relevant information, including where you heard the expression" (3 upvotes) Then, on reading the link, another commenter wrote mockingly "I first saw it at this link that completely and entirely explains it using clear language. What is the point of this question?" (4 upvotes)
(Today) This user does a typical mash up of misunderstanding common to learners, in this case, thinking just changes a verb's tense. First comment (1 upvote): What makes you think the word ‘just’ makes any difference? In “did you win”, win is not a present form; it’s an infinitive. You cannot have two finite forms in the same verbal unit. Also, e.g. means ‘for example’ (Latin exemplī grātiā ‘for the sake of an example’), so for e.g. means ‘for for example’ and does not make sense. (No decipherable - to OP - helpful answer here; mostly a rant.) OP replies: "I wasn't sure, that's why I'm posting a question.. and wow... this community is pretty harsh in the way downvotes are given."
A not unusual comment here: "1) please try searching before asking questions here. A 3 second google search will give you answers 2) don't combine multiple questions into one." Not the worst rebuke in the world, but not nice, either.
One unfortunate used y'all or something like it, enough to warrant this comment: "Mayhap thou shouldst attempt to recast thy queries in the second person singular, for surely the second person plural hath soundly defeated thee, yea unto uttermost incomprehensibility, here most readily taken as mortal insult to the very tongue thou wouldst so dishonor with thine unlettered scrivenings." (upvoted)
And my two personal favorites. #1. An OP misunderstood a passage in the King James Bible (pardon my anglais, but the KJV is a bitch to read). My comment: "Sometimes, when in doubt, it helps to have a more modern translation at hand to compare." The following was a reply to my comment: "The typography, morphology, syntax, and lexical items used in English Bibles (which are, of course, always merely translations of Greek, Aramaic, and Hebrew originals) represent nothing more than the translators' takes on the best way to represent something by current standards. Since "current" covers the last 5 centuries of English, this is, to say the least, a mess. Nothing in an English translation can be depended on; always consult the originals." (emphasis mine) Here is someone stating with authority that we are slackers if we read the Bible in our own tongue, and disregards the fact that we have no originals (that's correct; all we have are copies of copies of copies of copies of copies with who knows how many transcription errors.)
#2. This is a comment I got constantly for any answer which had no linked source: "-1 Always substantiate your "answer" with a canonical reference. Opinions are more appropriate in the form of comments, not answers." Meanwhile, the commenter was generous to others who almost never link sources. It was personal; but the point is, it was unfriendly. It was unkind. It was unpleasant.
This looks like a rant, but it's actually merely a substantiation of the OP's mild and wise admonition to be welcoming. This is a minute fraction of the insider (or insider wannabe) rudeness that occurs on this site.
In the time it took to write this answer, please note the quality of comment the OP got in reply to his post above, the number of views, and the number of upvotes. There must be something to his post.