When to use block-quotes, and when to not use block-quotes. Can someone clarify?
Most of our formatting is simply de facto convention, reflecting the preferences of longstanding members who edit and post frequently. While there was some early attention to formatting standards, e.g.
nothing like a formal style guide has come to fruition. Some individual questions of formatting have been covered in
Also related is
Based on my couple of years of participation here, I would say that blockquote formatting is liberally employed on EL&U. In particular, because this stack uses text examples rather than code, and because virtually every question and every answer entails drawing a use-mention distinction, authors and editors are very liberal with italics, boldface, block quotations, lists, and headings, and the case has been presented to add smallcaps as a further option.
The main exception is the widely and much-despised preformatted code format, against which tchrist has made a comprehensive case. They are tolerated in the rare cases where preformatted text is truly desired, as to simulate tables.
Because blockquotes are the most distinctive way to set off certain text from other, they are applied wherever a strong distinction is desired:
“Always” when the situation would call for the traditional use of a blockquote in written communication, for example
- quoting passages of prose, including other SE posts. It is not necessary to wrap images in blockquotes, even when they are images of quoted text, though some have out of an abundance of caution.
- quoting more than one line of poems or lyrics, though it wouldn't be necessary if somehow the poem constituted an entire answer.
- quoting dictionary definitions or excerpts from other references.
- providing example text longer than four or five words.
- providing multiple examples in succession, though this is not strictly necessary for readability when used in a bulleted list or similarly distinctive formatting.
Occasionally you will see it used to set aside the main question from its background information, or where headings would be more semantically appropriate but
the author just wants the text to stand out.
I don't myself endorse the latter uses, though I don't consider them so egregious as to edit them out. I do edit to insert them for readability in the first five cases; if you look at older posts from 2010 or 2011 before the conventions were widespread, you'll find many more solid blocks of text that are much harder to skim.