While agree with the broader thesis of this post, the part about gun ranges doesn’t jive with what I’ve read on US Navy doctrine, shell, and ship design. For starters, what I’ve read is that the decisive US Navy range they wanted to achieve was not close range, especially not the 10,000-meter mark you’ve claimed, but medium range, i.e. a band from 17,000 - 21,000 yards - and this would be preceded by fire at extreme range, I.e. 27,000+ yards, to disrupt the enemy battle line and perhaps get a few golden BBs.
Further, the idea that super-heavy shells were designed for close range and flat trajectories simply doesn’t match their actual flight characteristics. For flat trajectories, you want high muzzle velocity, but the modern 16” guns fired at modest to low velocities. Super-heavy shells instead had steeper falls and retained energy better, characteristics better suited for attacking deck armor than belt, though by any measure the SHS shells were excellent belt-punchers. Essentially, SHS shells were intended to gain an advantage in the initial extreme-range phase while still retaining excellent capability to handle the decisive medium range combat, as well as handle all sorts Wild and crazy obliquities.
The armor schemes of the war-built battleships also reflect this doctrine, particularly the much-hyped decapping plates the Iowa and South Dakota classes possessed. They worked, but they weren’t thick enough to work at every obliquity; below 20 degrees obliquity, they become a fifty-fifty roll of the dice against 16” shells. Considering the Mark 5 guns on the Colorado class (the best comparison for foreign guns) only hit that striking angle at 23,000 yards, that suggests to me that the decapping plates were intended to get the ships through the dangerous long-range zone (21,000 - 27,000 yards) and then aid them in the medium-range slugging match. More importantly, they’d be essentially useless at the ranges you’re describing.