Why Has the Typical Film Editor's Job Become More Involved

Why has the typical film editor's job become more involved in the last fifty years?

A) because film editing equipment has become more confusing and less effective
B) because audiences have become more discerning about discovering editing mistakes
C) because producers now interfere to a far greater extent in the editing process
D) because the art of editing is now rarely taught in film schools
E) because today's movies run longer and contain more individual shots