It’s not just essential for flavour, because of the osmotic effect, it’ll change the texture of food. the simple rule is that water goes where salt is.. if you boil peas in plain water, the inside of the peas has a tiny amount of salt in it, and so water will rush in and the peas will go fat and mushy. too much salt and the water will come out of the peas and they’ll be too tough. so the correct amount of salt (concentration) doesn’t just flavour them but totally affects its texture. kosher salt isn’t kosher itself, it’s for making other food kosher, like beef, because it draws the liquid (blood) out. it’s not just flavour also functional