Wikipedia:Disparaging
 | This is an essay. It contains the advice or opinions of one or more Wikipedia contributors. This page is not an encyclopedia article or a Wikipedia policy, as it has not been reviewed by the community. |
 | This page in a nutshell: Insulting or disparaging an editor is a personal attack regardless of the manner in which it is done. When in doubt, comment on the article's content without referring to its contributor at all. |
In that all pages belong to the whole project, any user may edit this one. But it's generally more helpful (and polite) to discuss the proposed change on its talk page first.
The quote in the nutshell above is from one of Wikipedia's fundamental policies. ([1], see the bottom of the section, emphasis added)
It could apply only to articles. But that's clutching at straws.
Every editor of any page should try to avoid disparaging other contributors. Which is not always possible. But every other editor should try to encourage them to avoid any personal attack.