I think Murch/Ebert are implicitly drawing a distinction between 3D being something people can watch without having a physical response and 3D as a viable techn

I think Murch/Ebert are implicitly drawing a distinction between 3D being something people can watch without having a physical response and 3D as a viable technique for making movies. I understood the argument to be twofold. Firstly, even if you don't get headaches, your brain is still working overtime, which makes your movie-watching experience less pleasurable than it would be if you were watching a true holographic movie. Secondly, because of the way the brain processes images and the illusion created by 3D movies, the technique limits the genre because one cannot use edits that are very rapid or have shots with a lot of horizontal movement. Whether that amounts to "not working" is perhaps up for discussion, but I think they have a point that the problems with 3D extend far beyond the fact that some people have adverse physiological reactions while watching.