Across the network, but especially on Stack Overflow, it's considered important to edit questions and answers to remove noise. Of course I agree with this policy; it's part of what keeps the sites working smoothly and in line with the goals described in the tour.
The problem is, there's far too much inferential distance between what the tour says - or stock pieces of advice that we're "not a discussion forum or a help desk" etc. - to a proper understanding of what "noise" is and why it should not be added to questions or answers (and should be edited out when encountered).
Time and time again on Meta, I find myself observing in answers that such and such content in a question or answer (was | would be) noise, and should be edited out. But that's the kind of claim that ought to be backed up by a canonical reference to policy, and my options are severely lacking. Worse yet, I have to say these things knowing that the Tour and the Help Center, as they currently exist, could not reasonably have prepared the Meta OP to expect such a policy.
When I try to explain why noise doesn't belong in posts, the best options I can find are things like Should 'Hi', 'thanks', taglines, and salutations be removed from posts? and Why are fellow users removing thank-you's from my questions?. But this is quite a stretch: there are many other kinds of noise beyond common social pleasantries, and the content is written from the wrong perspective. It's one thing to convince people that they aren't being oppressed by having their content edited on the Internet; it's quite another to teach the expected writing style to cut down on the editing burden placed on others in the future.
To address the latter, I cannot effectively refer to the Help Center, either, because the relevant entries simply don't say the relevant things about how the site works:
The Stack Exchange template how to ask page (unix.SE shown as an example) is brief, which is good, but it doesn't get into any kind of issues of writing style. "We like to help as many people at a time as we can. Make it clear how your question is relevant to more people than just you" is why we want to remove noise; but it's much too hard to infer "please just get to the point instead of talking about yourself" from that. Hardly anyone will infer "avoid redundancy, organize your thoughts, and try to value the reader's time". Stack Overflow gets a custom version that's much longer, but still completely fails in this regard.
The explanation of editing (this seems to be the same on Stack Overflow as on other network sites) is actively counterproductive. There's a list of common reasons for edits that doesn't say anything about noise, despite the sheer amount of noise and the value of removing it. Then there's a blurb discouraging "trivial" edits, which gives people ammo to complain on Meta about how some noise-removing copy-edit is really just a pointless switch-up in writing style. (I'm pretty sure I've even seen people argue that they intended to ramble about how they came up with an answer or to commiserate with the OP, and thus editing these things out of an answer is "changing the meaning".)
We need to update Help Center material so that people are directly told about these expectations, and have faq entries on Meta that properly describe the concept of "noise", explain why it is bad, and show good examples of noise-less writing.
[faq]questions on Meta to improve searchability.