I dont think anyone would debate that Sedans are more complex.
The argument that some are making is that the setup of a pan car, specifically, 12th scale, is more important than that of a Sedan to obtain a funtional, drivable car. Thus, where beginners tend to make mistakes in ride height settings, building crappy shocks with air in them, leaving the suspension binding, etc... This has a much more pronounced effect on the handling of a pan car than on that of a 4wd Sedan with independent suspension. These issues may not manifest themselves in a truly negative way with a Sedan... your Sedan may not be perfect, but it isn't going to be undrivable. The same cannot be said for a pan car that is setup so poorly.
Regardless, every has their own opinion about these things.