While I agree with most of your points, I do think many people fail by over-snippetizing code they post. In many, many cases I've seen, the part of code with an actual error is in the part that gets cut. I think a really good principle is to paste some stripped down version of the code (complete with enough variable definitions and data) that can actually be run by itself and produces the non-desired output. Often the mere act of composing such code answers the question, and if it doesn't, it greatly clarifies where the problem is.
That said, I agree that if "use strict;" and/or "use warnings;" doesn't affect the code one way or the other, it might be worthwhile to mention it as a guideline, but the absence shouldn't stop anyone from helping with the real problem.