Think about what salt does. What are we protecting the metals of our car from? The corrosive power of salt that gets put on our road. Hot salt water in your Hot Tub (ג׳קוזי) will do the same thing–it’s just what salt does.
The metal components of your pumps, your heater, perhaps even your jets in Spa Pool (בריכות ספא)can be affected by corrosion caused by salt. You may not notice it for a year, or even two, but I am quite certain that you’ll be needing replacements and repairs before long. If you’re lucky, they will still be covered under your warranty, but no one wants to waste the time with repairs and the risks of them being needed during the winter.
Why would you want to put yourself at risk of needing to completely replace heaters, pumps, wiring, etc, for a system that really does, essentially, use chlorine or bromine, just like many other chemical systems? Sure, it’s salt water, but salt is sodium chloride, NaCl. The generator separates it into salt and chlorine, simple as that. When used up, the cycle starts again. The equipment in your Jacuzzi (ג׳קוזי) should last you many, many years with regular maintenance. With a salt water system, it may last as little as 2-3 years.