Bullshit is a requirement to keep groups together. Thats much more useful than intelligence. Its really a signal of group binding capacity.

We hire Bullshiters to run around 24x7 to tell people what they should be scared of, what they should love, what numbers they should hit, what status they should aspire to, what flag they should die for etc because left to themselves they will come up with very different answers.

Given the variety within the chimp troupe, in terms of personality traits, needs, backgrounds, skills, taste etc there is no good reason why groups wont drift apart with time. Unless the Bullshiter is on patrol 24x7.