I like you. Good explanation. To add to that; like you said Flour is "100%" or 100/100. So when a recipe calls for 2% salt, it's looking for 2/100 salt. Since we know the weight of the flour is 100%, then we can multiply the weight of the flour by 2/100 or .002.

This is only really relevant for up / down scaling recipes. If I need to make a bunch of loaves and decide I'm just going to use the remainder of my bag of flour suddenly my recipe is:

flour: 100% = 3628g
Water: 72% ???
Salt:3% ???

It's much easier to change the recipe by multiplying 3628g by .72 and getting 2613g than trying to mess around with 1/4 cups and teaspoons.

I hope this helps anyone!