In my opinion, it really depends on the subject matter. For an encyclopedia, inline arguments are surely the wrong thing. But in that case, you're really using a wiki-like system as a more user-friendly, accessible content management system.
And for things like c2, I'd consider the lack of threading an advantage. For lots of technical discussions, this leads to clarifications that are hidden somewhere deep in that thread pile and would require an editor to factor those out in the main article. Which works fine with something that has a huge user base or paid people to work on it (i.e. Wikipedia or corp "wikis"), but not for everything.