|This page in a nutshell: Editors are encouraged to write the article on a given subject BEFORE adding a link to the article in list pages, disambiguation pages, or templates. New articles must satisfy the notability guideline and core content policies.|
Wikipedia editors should write a new article before they create links to that article in list pages, disambiguation pages, or templates in the encyclopedia. Frequently, editors (mostly inexperienced ones) add wikilinked entries in lists, "See also" sections, navigation templates, and disambiguation pages. If such an entry links to an article that does not exist, the result is a red link like this one. When the editor goes on to create the new article, the red link in the list turns blue, and assuming the article follows Wikipedia's practices (such as notability, verifiability, and other relevant policies and guidelines), everything is fine.
Creating red links in purely navigational features of Wikipedia, like navigation templates, disambiguation pages, and "see also" sections, directly interferes with the actual function of these features, which is to help readers navigate the already existing Wikipedia resources relevant to the topic. Red links are strongly discouraged in navigation templates and disambiguation pages, and they are never used in "See also" sections.
The principal rationale for adding a red link to a disambiguation page is that the entry added is definitely notable, will probably have an article eventually, is not covered by any extant article as a subtopic or section that can be linked to, and yet is something that a non-trivial number of readers may actually be looking for at the name being disambiguated. As Wikipedia's coverage expands, these criteria are less and less frequently met by would-be red links that editors consider adding. Lack of notability is the most common point of failure, and many such entries are deleted as essentially promotional in nature, often having been added by someone with an apparent conflict of interest. Wikipedia probably does not need a disambiguation entry for your band's new album title, or a vice president at the company you work for, and if either the band or the company already have an article, a disambiguation entry that blue-links to that article is better than a red link that goes nowhere.
Adding red links to navigation templates is tolerated when the missing article(s) are part of a set or series, and the template mostly consists of blue links to real articles (or article sections). Other red-linked additions to nav templates are generally a bad idea. So is adding a red link to a non-navigation template; templates are intended to provide functionality, so if your template's functionality is broken, it is not ready for use in the encyclopedia's content.
While lists (especially stand-alone list articles) can serve a navigational function, lists are primarily a form of encyclopedic content. Thus, an entry often may simply present encyclopedically relevant facts from the cited reliable sources and not link to a separate article on the narrow subtopic (which by itself might be encyclopedically relevant but fall short of independent notability) of that particular list entry. One of the main distinctions between lists and article categories in that lists may contain non-notable entries (although many lists' inclusion criteria are not so broad). Consensus on how helpful or pointless red links in lists are has been a moving target on Wikipedia for a long time, but including them has a large number of detractors. Red-linking within lists is only helpful to editors, not readers, and is only useful when the red-linked topic is certainly notable and should have its own article; there is no point whatsoever in red-linking to relevant but non-notable subjects, since their non-notability precludes them having their own articles and thus ever having blue links. Also, the continual addition of unsourced entries of questionable encyclopedic value – "list-cruft" which can lead to the creation of "laundry lists" – is a continual cleanup problem.
In the early days of the project, before the notability guideline even existed, a "red-link with impunity" approach was an important part of jump-starting the encyclopedia project. Long "Lists of topics" (also called "Index lists"), sometimes with all red links, were among the first articles created. Now, however, with the English-language Wikipedia at 5,981,839 articles, list articles with many red links play almost no role in leading to the creation of new articles. Instead of using stand-alone "Lists of topics" articles as guides for the creation of new articles, editors have largely moved this function to wikiproject pages that cover specific areas of interest.
As a result of the early Wikipedian approach, editors who these days add red links to lists often have no intention of ever themselves writing the red-linked articles. This may be simply because writing an article is much more time-consuming than adding the link to the list or template. "Someone else will do it", the editor reasons. Or the editor may be choosing to contribute anonymously, which means they cannot directly create an article, having to use the Wikipedia:Articles for creation process instead, and wait for their draft to be assessed. Lastly, it may be because the editor knows, maybe even from first-hand experience, that newly created articles that do not follow Wikipedia policies and guidelines can be deleted, whether or not the editor is aware of Wikipedia's new pages patrol or is familiar with the details of the speedy deletion process or other deletion processes.
It is this last reason that is the most problematic: "List of..." and "Comparison of..." type lists, both stand-alone and embedded, are often prone to spam and red-linking. In many cases nearly half of the edits are limited to adding spam and red links to the list. A large proportion of the later edits will be removing them, which, while critical to maintaining the quality of the page, is a tremendous waste of WP editor resources. Lists are used in Wikipedia to organize information, and sometimes for internal navigation. Lists with a primarily navigational purpose should only contain internally linked articles, thus serving as natural tables of content and indexes of Wikipedia. Whether in the form of "List of..." or "Comparison of..." (among other formats), lists are subject to Wikipedia's core content policies, like WP:Verifiability, WP:Neutral point of view, and WP:What Wikipedia is not (see especially WP:NOTDIR, WP:LINKFARM and WP:IINFO), as well as site-wide guidelines, like WP:Spam, WP:Conflict of interest, and WP:Identifying reliable sources. Ask any editor who watches list pages – they will likely have had the same experience. Far too many lists are full of this spam, with no end in sight, often more red links than blue. List of demoparties has long been one example.
Because of both of the above, editors are encouraged to write the article first before adding it to a list, template or disambiguation page. Don't worry that the article, even if it is just a stub with only a couple of sources, will be exposed to the new pages patrol, which, after all, is much more focused on article improvement than on article deletion. The new article you create will be improved by other editors. Helped by these improvement processes, you can be sure the article is list- and navigation-worthy, and can then place a link to it on the appropriate list(s), template(s) and/or disambiguation page(s), confident the link will be blue from the beginning.