I don't even understand the people claiming it can't be a true story, what are you saying? all of that was fabricated? the gallery? mr. brainwash is still a thing, he still makes shitty ripped off art, Madonna did indeed use his work as a cover to her album haha. the LA show..are you saing that was fake? it is pretty obvious, that Theirry was Banksy's own experiment, Thierry is a real, bizarre, kind of not so bright person, that Banksy manipulated and used him to satirize and mock the 'art industry' and the commercialization of art (not that it hurt Thierry in any way, he made plenty of money). he set him up entirely - Banksy was even more of a puppeteer than they portrayed in the documentary but they talked about that blatantly numerous times, so I don't completely understand the controversy here. The last part was indeed a ruse, if you watch the documentary I don't see how you can miss that. But how does it being a ruse make it not true? the entire point of the movie is how ridiculous the 'art world' is for placing value judgments on things that have no inherent value, just perceived value. It's all about perception and art, and how the two are completely interwoven.

why are people so up in arms about this being 'fake,' when it is just good story telling?

a simple google search will yield hundreds of articles, all concluding that the events that took place in the film absolutely happened: http://articles.latimes.com/2011/feb/22/entertainment/la-et-oscar-exit-20110222/3

it seems more implausible to me that this was completely faked (If that's what you're saying?) - basically I agree with the last part of your comment but the first part confuses me