The answer depends the severity of the problem and opinion of each editor. Wikipedia obviously requires some minimal standards like, say, complete sentences. But iterative development is a key part of the process. Many in-depth articles once began as very short, undoubtedly incomplete entries called stubs. Similar to the debate about inclusionism vs. deletionism (see week 21) is the question of immediatism vs. eventualism. When you're writing an encyclopedia that will never be printed yet is constantly published on the web, how good does it need to be right now?
In Wikipedia's early years, there was a higher degree of tolerance for incompleteness and errors. Since then, Wikipedia's growth in popularity and resulting scrutiny has arguably changed the equation. And yet, the limited base of editors makes eventualism less of a choice, and simply a fact of Wikipedia life.