I wholeheartedly agree that MB casts the 16 people with archetypes in mind, and he anticipates conflict (Frank and Brandon were not randomly placed together, IMHO... nor were John and Paschal, but in that case the desired result was not achieved). The cast must be created with a vision of how they will interact, and how they will behave.
Unfortunately, a 20 minute (or however long it is) video made in your basement or backyard is not the same as a beach in the jungle (case in point: Stephanie from Thailand). It is here that the editing takes the front seat.
The whole point of taking these 16 people and putting them in the Amazon for 39 days is to make a television show. However, there is a key difference between Survivor and a documentary: in general Survivor has a story to tell (and in many instances, several stories) while a documentary is produced solely to document an event or events.
Sometimes, the story tells itself, and the actions of the characters is sufficient to convey the message. For example, one of the messages in this week's episode was conflict in the women's camp... Christy and Joanna provided MB with footage to use to convey this fact. He had no editing to do here, save to splice some footage of Jeanne and Janet looking concerned or disapproving.
However, if we delve into other instances, perhaps from another Survivor (say Australia), we see a different situation. Jerri was cast as the bitch/villain. Keith, her unwitting victim. Throughout the first few episodes we were treated to snide comments from Jerri about the chef who cannot cook rice, from Keith about the wannabe actress criticising him, and finally a threat of a "time out" from momma Tina. All these events really did happen; and up until the recap episode, everyone thought that after Survivor was over, we would get Celebrity Deathmatch: Jerri vs. Keith on MTV. Instead, we see Jerri apologise to Keith on the recap. We see them bury the hatchet (more or less). So when did this occur? Was this just a day before (in the show's timeline) the recap episode? No. It happened at the Ogakor camp, and by the time the recap had come two of the Kucha members had been tossed from the merged tribe. The choice of omitting that one scene of resolution completely changed the perception of the group dynamic of the Ogakor 5 -- everyone was watching, waiting for the emotion to boil over, and for Keith to rat out Jerri and vote her out with the Kuchas (or Jerri to do so to Keith)... but it didn't, because there was no emotion left to boil over.
Disclaimer: in an effort to explain myself, I often become quite verbose, and rather analytical. In no way am I advocating such in depth analysis of each and every scene to see what is "missing". I am, however, suggesting that what we see be taken with a grain or seven of salt, so that we are more aware of the potential for misdirection.