The Wikipedia promise is "edit this page."
But I don't think the promise of zero-threshold _editing_ should automatically be a promise of zero-threshold article _creation._
_Most_ people get their feet wet with simple edits, giving a chance to get acculturated before taking the leap to creating an article. People whose first edit is the creation of an article are, I think, showing _too_ bold a temperament.
Many online communities have a provision whereby new users' messages are automatically moderated initially and only removed from moderation after they've posted a small number of acceptable messages.
Suppose we had a level of privilege called, say "contributor." Anons and non- contributors could edit articles just as they do now, but only contributors could create an article _and have it appear immediately in the main namespace._
Articles contributed by non-contributors would go to a "moderated" area. These article would not appear in the namespace until a contributor made at least one edit to them. That is, an article is approved by making a single edit to it. The reason for requiring one edit for approval would be to strongly encourage contributors not to mindlessly approve marginal articles.
I'm thinking that it should be extremely easy to become a contributor. I'm thinking that the requirement should be a) contributors must have user names, and b) users with accounts get contributor status automatically as soon as their first new article is approved.