Marc Riddell wrote:
If I want to question the substance of an Article in Wikipedia, I should be able to go to an editor¹s personal information page and get a sense that they have the expertise to be editing the material, and a page where I can contact them with questions. Every, reputable reference work has this.
Every registered user has a page where they can be contacted with questions. Mine, for example, can be found at http://en.wikipedia.org/wiki/User_talk:Gurch . Users are also permitted to set up personal information pages, though these have a wide variety of uses; mine is more a collection of navigational links for my own use than information about me. See http://en.wikipedia.org/wiki/User:Gurch . Anonymous users can be contacted with questions in the same way, but since many of them share IP addresses and/or change IP addresses frequently, and having added information may not even check the site again for months, they may never see your question.
If you want to question the substance of a particular article, though, it's best to use the article's discussion page rather than any particular user's discussion page. The part of the article that you wish to comment on may have been put together by dozens of different users, and singling out one isn't always the best way to get feedback.
-Gurch