The counterfactual delays the treaty system long enough for the new British designs to enter service. An N3 with 18-inch guns would present such a threat that much of the contemporary US battlefleet could appear outclassed. G3's 16- or 16.5-inch guns seem a smaller step, but their combination with battlecruiser speed changes the comparison. The US Navy already treated Hood as equivalent to one of its 16-inch battleships. A new capital ship can destabilize fleet planning through its speed and choice of targets as well as its gun calibre.
Notable Point · 10:24-11:24
Why G3 and N3 would disrupt rival battlefleets
An 18-inch-gunned N3 or fast G3 would have forced rival navies to reassess whether large parts of their existing battlefleets still had first-line value.