Yup, salt went in lots of things from dishwash, shampoo, conditioner…you name it, it’s only purpose is to ‘bulk’ out very runny liquids for a more ‘luxurious’ feel. Now it’s glycerins that are more prevalentDon't know if it's true but many years ago I read that dish wash liquid is bulked up with salt? The same article went on to say it was one, of several, reasons why you should never put it in your screen washer reservoir as it gets into the bodywork seems and greatly accelerates rusting? I've also read that genuine screen wash contains additives to protect and lubricate the pump, wiper blades etc. All my children got the "only use proper screen wash fluid" lecture.
Organic gloopy gunge build up in washer bottles used to be quite a big problem which would block up the fine mesh filter on the intake to the pump, especially where the owner didn't use the washers very often. For this reason we would stick the mains hose right down into the reservoir and let it run full blast for a couple of minutes at every service before refilling it with fresh fluid. To this day I do this on all our cars and only my boy's Astra has ever suffered a blockage within recent memory. Used to be easy to take a reservoir out for cleaning but some of them now a days are a real pig to do. I can see Twink's from under the front but no idea how you'd get it out! The filler disappears down the inner wing to the "front" of the engine.