I get what you mean about MMO's, but I wouldn't use the term "assembly line" - rather I would say they are highly choreographed events. Speaking as a former Vanilla WoW Choreographer (Raid Leader) I can attest to the difficulty in getting 40 people to all do the correct thing - depending on roles - for 2-10 minutes.
The most difficult raid I was ever involved in required five people to each press a coloured button in an order that would be given to you, but it was randomised each time, and you had a limit on how long you could take to do it. And we had to do it correctly at least five times to succeed. On it's own, this would not seem like a big ask, but sometimes trying to get a bunch of gamers to do something specific, or even Wait Their Turn (absurd), is like trying to get 12 cats into carriers all at once.
