I think the use of the term "documentary" is a little over-generalized here. To shoot in a documentary style is possible with -any- camera system, I do it with a Hasselblad on a tripod, I do it with a 4x5, and I do it with all my 35mm cameras. I would also hardly say that what is being shown at the higher echelon galleries is "documentary" at all. I see a lot of color. Color and appropriation. Take for example Gursky, or the bullshit wanker known as Richard Prince. Gursky is big color, Prince is big bullshit. I'm far more concerned about the people who -do- take all the considerations and time in the world to iron out an idea that was poorly conceived in the first place. Let the bad ideas bleed quickly, so that the photographers/artists producing them can evolve their talent to a higher level.
Digital flourished because it was convenient and accessible. Custom black and white photography became a reality for the every day snapshot shooter with digital, as well.
Also, any list of suggestions with a title as smarmy as that (and believe me, I've seen them), should immediately be ignored and filed under "useless".
I've never gained insight about the art world from anything like that, but from looking at actual artist books, as well as applying unrelated literary material into my beliefs and philosophies. I think reading Ayn Rand's The Fountainhead and picking up a camera as a result of not being able to draw fast enough, made me a better photographer than any of Saint Ansel's technical books ever would have...