I agree with this to a large extent. But I think when you write about a work using only the work itself as a source you necessarily *do* put forward this sort of synthesis. Otherwise, what is the point of mentioning the fact?
I have noticed you say this or something like it a few times. Throughout this thread you seem to be arguing that you cannot use a work as a source for itself. But, every time someone points out an instance where you clearly can, you revert to "... write about a work using only the work itself as a source ....". Which is your position? I agree that is almost every case, you are right with the modified "only source". It would not make much of an article if you simply said very shortly what happened and which characters where there etc. However, that is quite a different thing from using it as a source for individual facts--which characters where present in the first episode as compared to the last, how many seasons the show ran, etc--and using other sources for the other facts needed to make the article readable.
Dalf