With respect, this is simply not true. "Salt" is a term that should not be generalized. Processed, bleached and furnace heated table salt is toxic. It has no minerals and has anti-caking additives that are poisonous. The immune system has to work to rid the body of it since it is viewed as a foreign toxic substance. Ancient mined salt with minerals intact is necessary for life, and has been valued by humanity unchanged until the last few decades.
As with most things, the processing of salt is purely for the gain of the corporations. Where do you think the mineral supplements we buy and the minerals that "fortify" all our food comes from? Right. Salt processing companies.
Cosmetic? No. The eyes are a clear manifestation of your health, as are teeth and gums and the nails and hair.
What do horse doctors check to determine health? (This is my experience, probably true for all animal vets.) Eyes, teeth, hoofs, nostrils (uncongested breathing), coat.
You can determine people health quite easily in the same way.
The only thing other than health and diet related that helped my eye bags (hydration and parasite cleanse) was facial exercises.
Specifically, a lower eyelid flex, where you flex just the lower eyelid 10 or 20 times then hold it for as long as you can. This helps circulation and also strengthens and tones the muscles in that area.