Have a look at this long, thorough evisceration
of the muddled, contradictory illogic of Michael Moore's "documentary" work, courtesy of Christopher Hitchens.
I suggest you read the whole thing, but this paragraph sums the essentially point about Moore...that while trying to be both, he's not only a shitty journalist but a lousy artist as well:
Some people soothingly say that one should relax about all this. It's only a movie. No biggie. It's no worse than the tomfoolery of Oliver Stone. It's kick-ass entertainment. It might even help get out "the youth vote." Yeah, well, I have myself written and presented about a dozen low-budget made-for-TV documentaries, on subjects as various as Mother Teresa and Bill Clinton and the Cyprus crisis, and I also helped produce a slightly more polished one on Henry Kissinger that was shown in movie theaters. So I know, thanks, before you tell me, that a documentary must have a "POV" or point of view and that it must also impose a narrative line. But if you leave out absolutely everything that might give your "narrative" a problem and throw in any old rubbish that might support it, and you don't even care that one bit of that rubbish flatly contradicts the next bit, and you give no chance to those who might differ, then you have betrayed your craft. If you flatter and fawn upon your potential audience, I might add, you are patronizing them and insulting them. By the same token, if I write an article and I quote somebody and for space reasons put in an ellipsis like this (…), I swear on my children that I am not leaving out anything that, if quoted in full, would alter the original meaning or its significance. Those who violate this pact with readers or viewers are to be despised. At no point does Michael Moore make the smallest effort to be objective. At no moment does he pass up the chance of a cheap sneer or a jeer. He pitilessly focuses his camera, for minutes after he should have turned it off, on a distraught and bereaved mother whose grief we have already shared.