Why would I put "salt" in my dishwasher? TFA has the answer, it's to soften the water: 'Special dishwasher salt, meanwhile, helps to "soften the water prevent

Why would I put "salt" in my dishwasher? TFA has the answer, it's to soften the water: 'Special dishwasher salt, meanwhile, helps to "soften the water preventing lime scale build up and those horrid white marks on glasses."' In the U. S., if hard water is a problem then the house probably has a whole-house softener, and "dishwasher salt" isn't necessary.