I had done some more research since I contacted you and pretty much answered my question.
Shoes are actually made for your arch length; Manufacturers simply count on everybody having regular sized toes. The arch length (heel to ball length) doesn’t concern most people (hence why I and almost everyone else hasn’t heard of it), because most people have arch lengths that correspond to their foot lengths (in other words, they have “normal” sized toes). There are some people, however, who have extra long or extra short toes. This makes the arch length and foot length very disproportionate (short toes correspond to a long arch length and long toes correspond to a short arch length).
I have short toes in proportion to the size of my foot, so the length of my foot will fit well into a size 15 shoe, but the break of my foot is much higher up than the break of the shoe. This makes the shoe too tight on the ball and presses the toes together. The widest part of your foot us supposed to match up with the widest part of the shoe. This can cause big problems in the future and could be part of the reason why I have mild bunions on both feet.
On the Brannock Device, the heel-to-ball measurement is on the opposite side of the width bar. The numbers correspond to the shoe size. When I measure the length of my arch on the Brannock Device, it goes off the chart. My arch length corresponds to between sizes 16.5 and 17. This is the size I’m supposed to wear, even though I will have extra room in the toe box.
People with extra long toes have a special problem: If one’s arch length corresponds to a size 11 but their foot length corresponds to a size 13.5, they can’t simply go with a size 11. Their toes would be squished. These people either have to buy a pair of shoes that are too wide for the rest of their foot to accommodate for the ball, or they have to find a shoe that has a extra longer toe box.
Hopefully that made sense lol.