I'm sure both SO and Wikipedia have their own dysfunction even within the constraints of their stated policies, which I'm sure is a constant struggle to deal with. But that's inevitable, communities always have issues to deal with. Those are different issues than users wishing a site had different goals. I'm all in favor of sites like SO or Wikipedia (or Reddit, or HN) having all sorts of constraints on what types of content they want and how they operate. Maybe it's frustrating sometimes for people who are set on relying on one of those sites for everything (and therefore want them to be all things to all people), but overall I think those types of self-imposed constraints are exactly what makes them useful and interesting, and allows them to grow in ways that are unique to the mission of the site.