Do I have to name all editors when reusing text from Wikipedia and SE?

Question

Wikipedia writes that

You should not cite any particular author or authors for a Wikipedia article, in general. Wikipedia is collaboratively written. However, if you do need to find the list of authors of a particular article, you can check the Page history. Authors are listed only by IP address or chosen username; you normally cannot verify and often cannot even guess at their identities.

Is this not in contradiction with the CC-BY-SA 3.0 license under which individual authors provide content, though?

You must attribute the work in the manner specified by the author or licensor

From what I understand, when I write text on Wikipedia I can specify a name under which I would like to be credited and a canonical URI for my work.

Is a link to Wikipedia sufficient to fulfil these obligations, even if the username of the editor is hidden in the page history behind several clicks? (And, also, the page history can be deleted?)

For another less contrived example about the "link-only attribution" being deleted: suppose I find an answer in a comment on Stack Exchange. SE content is also licensed under the same CC-BY-SA-3.0 license (or at least recent content). As good practice demands, I copy that text into a Community Wiki answer, and use a permalink to the comment as my only means of attribution. Later, the comment gets flagged as "no longer necessary" and deleted, so my perfectly legal means of attribution disappears forever. Who is at fault here?

Answer 1

Wikipedia is the Licensor who are granting you the license, thus in the text you quoted:

You must attribute the work in the manner specified by the author or licensor

the manner specified by Wikipedia in the link you gave is the way you must attribute the work.

When a person contributes content to a Wikimedia project, they agree to license it under the CC-BY-SA-3.0 license, but they also agree to be attributed "in any of the following fashions... i. [through] hyperlink (where possible) or URL to the article to which you contributed (since each article has a history page that lists all authors and editors)" (see Wikimedia Foundation, "Policy:Terms of Use — 7. Licensing of Content").

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See section 1(f) of the License used for the definition of the Licensor

Answer 2

Your question asks what you must do. To get to the "must" part, you look at the terms of use, and consult non-binding normative recommendations only when they are incorporated into the license agreement. The license is here. The first step is to understand the author's license to Wiki, that

When you submit text to which you hold the copyright, you agree to license it under: Creative Commons Attribution-ShareAlike 3.0 Unported License (“CC BY-SA”), and GNU Free Documentation License (“GFDL”) (unversioned, with no invariant sections, front-cover texts, or back-cover texts). (Re-users may comply with either license or both.)

Under the terms of CC, that means that nobody in the chain of licensees can change the license, and "You must give appropriate credit". This also means that Wiki does not get to impose additional licensing restrictions on contributor content. They are, however, free to make recommendations as indicated by their use of the word "should", not "must" or "shall".

Wiki does not claim to have a special licensing relation with the author. Often, content is uploaded to a provider who is granted a license to redistribute, and that provider then sub-licenses the content to the world. Wiki does not do this: the author's license simply says "you agree to license it", not limiting the scope of the license. Therefore, any contribution that you make on Wiki is directly licensed to any and all users – Wiki does not purport to add or subtract anything from those two licenses, and you do not sub-license from Wiki.

Wiki can, however, ban you if you don't comply, in case there is a putative contradiction in licensing requirement and they think you have violated their rules.