This is an essay.

It contains the advice or opinions of one or more Wikipedia contributors. This page is not an encyclopedia article, nor is it one of Wikipedia's policies or guidelines, as it has not been thoroughly vetted by the community. Some essays represent widespread norms; others only represent minority viewpoints.

If a topic is worthy of a wikilink, why shouldn't the wikilink be to a standalone article?

The technique of creating wikilinks to subsections headings is heavily used in the wikipedia namespace. The technique is lightly used in article space. In my opinion this technique should absolutely never be used in article space, because the wikimedia software only partially supports this kind of wikilink.

The technique violates the principle of least astonishment

The technique of wikilinking to a subsection within an article violates the principle of least astonishment, because it erodes the reliability of the back button.

When one of our readers clicks on a normally constructed wikilinks, if they find they arrived at information that was not of interest to them, after all, a single click of their back button takes them back to where they started.

Even very inexperienced wikipedia readers will be very used to this behavior from their back button, as that is how regular plain-old links have always worked on the regular world-wide-web.

But when a reader clicks on a wikilink to a subsection within another article clicking on the back button works counter-intuitively. It takes them to the top of the target article. It does not return them to the original article at all. This is highly annoying if you know why the back button will sometimes fail to work properly. But for the vast majority of victims it will merely make the wikipedia look unreliable.

Since those who create wikilinks to subsection heading almost always create those wikilinks as "piped links" the odd behavior of the back button is even less predictable and transparent.

The technique erodes the value of the "what links here" feature

The technique of wikilinking to subsection headings seriously erodes the value of our very powerful "what links here" feature. "What links here" only works on the article level. Often the wikilink to a subsection heading is created when an adequate and policy-compliant standalone article is unnecessarily merged into a related article. Unnecessary merges represent a grave disservice to wikipedia contributors and readers who use our watchlist feature. So long as there were two separate articles, for the two separate topics, readers could choose to place just one of those articles on their watchlist, when the weren't interested in the related topic.

The technique erodes the value of maintaining a watchlist

We currently have no mechanism to place just a subsection of an article on our watchlist. Until we have a mechanism for watchlisting mere portions of article I think we should exercise caution over merging related articles without strong reasons for doing so. This kind of

The technique of wikilinking to subsection headings seriously erodes the value of our very powerful "watchlist" feature. This feature too only works on the article level.
The technique of wikilinking to subsection headings seriously erodes the value of our very powerful redirection feature. One of the strongest advances of wikipedia articles over the plain old links of the world wide web is that when a web designer on the world wide web changes the url to a web page, by even a single character, all incoming links to that page break. The web designer has no good way to know how many incoming links the name change will break. They have no good way to know how often those incoming links are being followed. But normally formed wikilinks to wikipedia articles are much more robust. When we move (ie rename) a wikipedia article, a redirect is automatically left behind. Thus incoming wikilinks continue to work -- without any effort on the part of readers or authors. Robots quietly fix double redirects. The incoming wikilinks are very robust -- unless contributors use the incompletely supported technique linking to a subsection, those wikilinks will break, when the subsection heading is changed. Even hard to notice spelling changes, changes in punctuation, or capitalization will break the wikilink. Contributors thinking of editing a section heading have no way of knowing that the section heading is the target of a non-standard wikilink.

There are contributors who promote the use of the incompletely supported technique of wikilinking to subsection headings, who recommend those who create such wikilinks should use an html comment at the subsection heading that is the target of an abnormal wikilink, telling other contributors the subsection heading is the target of a wikilink. But, in 9 and a half years of contributing to the wikipedia I have never seen anyone actually follow this recommendation. And even if someone did follow this recommendation, html comments are themselves so uncommon I really doubt anyone considering changing the subsection heading would recognize they should read the comment first.

Please, people contributing to this article, do not use this incompletely supported technique!