The documentary definitely was weird with the Brawl stuff. But the stuff about Sakurai wasn't exaggerated at all, and I think "Melee community created the Brawl community" and "there were like 10 people from Melee" are equally exaggerative. I also think Brawl almost did kill Melee, but yeah, it's not like that was "Brawl's fault," or the Brawl community's fault, or anything like that. It's just what happens when new games come out.
The documentary is a fun watch, but a few things did irk me. That was one of them, but also the complete glossing-over of Armada and the mostly glossing-over of Hungrybox (the two of whom make up what i naively consider to be the best rivalry in the history of fighting games). The overall tone of it is kind of amusingly overdramatic, which has its strengths and weaknesses, but I do think it would be difficult to watch this as someone who isn't already interested in competitive fighters!