Wikipedia:Noinclude considered harmful

The issue described by this page is no longer relevant due to a 2005 software upgrade.

If it is plausible to assume that people may Subst a template, do not give it a noinclude section to include usage help or categorization. Instead, use the template's talk page. Many templates such as afd and user are frequently subst'ed, and thus any noinclude section on them would not work as intended.

Noinclude can cause inappropriate categorization or formatting in pages including a template, if someone substs in the template and it contained a lengthy 'help' section under noinclude. That's what template talk pages are for. Noinclude sometimes does things that people don't expect it to, because people don't take subst'ing into account. That doesn't mean that one should never use noinclude, but that one should think twice and not use it blindly.