On the one hand: Stack Exchange encourages people to edit both questions and answers
As I've pointed out in previous versions of this discussion, the biggest problem here is that this is a highly creative Stack and edits are easily in conflict of a basic Stack Exchange editing rule. From the Help Center we read...
Edits are expected to be substantial and to leave the post better than you found it. Common reasons for edits include: ... To clarify the meaning of the post (without changing that meaning) ....
That parenthetic is 99.9% of the problem here. Edits are encouraged if and only if you don't change the meaning of the post. On this stack, it's incredibly easy to edit a question or answer and change the meaning of the post.
Let me say that again because I don't think enough people really understand it or respect it.
On this Stack, it's incredibly easy to edit a question or answer and change the meaning of the post.
On the other hand: this isn't Stack Overflow
On technical Stacks like Stack Overflow it's fairly simple to edit any post to clarify that post. Here, that's simply not the case.
It is my opinion that for this reason this Stack has developed an unofficial culture of not editing. That's not necessarily a bad thing. Nobody likes their baby called ugly. But if you're looking for community consensus to blithely edit other people's posts without their consent, here are (IMO) the basic rules by which it will happen.
You will not put words into the OP's mouth. Ever. Not for any reason. You can't "fix" the question or answer by changing it to be what you think the OP "means." You cannot pretend to read their mind, understand their psychology, or "get them." When someone posts a comment that expresses the frustration, "something's wrong with this, I don't get it," no matter how convinced you are in your own head that you're 100% clear on what the post means you won't change the post to reflect your belief. Not ever. (It is factually impossible for me to say this enough or in harsh enough language.)
If after a very small number of tries (2-3) it's found that you are changing the meaning of people's posts (and no amount of, "look, I understood what the OP meant even if you didn't" arguing will change this), your account will be suspended for 4 months.
If after a single suspension and restoration of rights you're found to do it again. Your account will be deleted.
If you think those rules are heavy-handed, you should be aware that I'm a fan of the Good Book, wherein a simple wisdom can be found, "where much is given, much is required." If you want the community to trust you with the creative input of anyone, great or small, you will be held intensely and immediately responsible for it.
However, if that level of personal responsibility isn't your cup of tea...
I am a fan of editing for formatting. Most notably to convert an illegible wall-of-text to a legible series of paragraphs, bullets, and headers.
I am a fan of inserting links to help future readers understand an esoteric word or phrase. Note that I do NOT change the original wording. All I do is add the link. (e.g., changing "link" to "link").
I am a fan of asking the OP for permission to edit for content. (And if the OP doesn't answer quickly, or at all, I'm a fan of NOT editing the post.)