Generally, this link from the WordPress SE says that answers just linking to a solution are wrong per the faq#deletion:
Answers that do not fundamentally answer the question may be removed. This includes answers that are … barely more than a link to an external site
Those answers should be made a comment if useful or removed if not, so says Rarst ♦.
I agree with him for there, but am not quite sure if this is / should be the same here. What about links to Wikipedia, App Notes, datasheets, and other texts or documents that are widely used, maintained by big organizations and generally considered to be accessible in the future as well?
For example, look at pjc50's answer on Save energy with PIC project. I consider this answer to be useful, though it's nothing more than a "yes" and a link to where the "yes" is explained. Also see this question which is basically screaming for app notes, which are given in this answer.
There's a vague line between "barely more than a link to an external site" and "very useful, official documentation".
This meta-question is intended to give support on how to treat answers like the two linked above.
Related: the problem of answers with links