"Systems resist change that threatens existing coordination patterns.
The word coordination is the hinge. In a system boundary decision that affects two teams, it tells you which part of the situation is structural, not personal. That is the part you have to design around.
In a system boundary decision that affects two teams, the failure mode is rarely ignorance. It is choosing as if the system were simpler than it is, then being surprised by the interaction effects. You see it in a boundary shift that moves work onto a team that did not agree.
Herbert A. Simon is a reminder to keep it concrete. State the non-goal and the boundary that keeps scope from turning into a rewrite. Make it specific enough that a peer can disagree.