This assumes pair-wise communication, but if you need to set up n-team cross channels then this can go up factorially (realistically it won’t, but definitely larger exponent than 2). To put it another way, thinking of teams as nodes and communication channels as edges doesn’t capture the possible complexity. It’s also not uncommon, I’ve had to work in cross-team environments where getting multiple teams aligned wasn’t just a series of pair interactions.
Not necessarily, Alice, Bob and Charlie talking together might not be representable through a set of <AB>, <AC>, <BC> interactions, sometimes you really need all three to be talking/listening together. Then the interaction is <ABC>.
This problem also appears in some physical materials where there are strong electron-electron correlations and so you can’t rely just on pair correlations for your calculations.