One point is one way to fail
Every control has a defeat. Lean the whole facility on a single one and you have handed an attacker a single thing to solve. That is the flaw in most single-line specs. They read as security on paper and give way the moment someone treats them as the only obstacle in the path.
Fire, ballistic, and forced-entry risk get reviewed separately, so the fix for one quietly undercuts another.
Work the risks in the same room
When those reviews happen separately, the choice that satisfies one can quietly weaken another. Set them against a shared threat basis before the materials are locked, and the protection holds together as a system rather than a set of parts that each looked fine on its own.
Built to one threat basis, that calls for materials specified as part of that system.