Zodiac SWG - Do I really need Salt Saver, Salt One, etc.

[waterbear]

Do you need to add them? In a word, no. If you want to know why they are being recommended it's because the more chemicals the store can sell you the more money they make.
The basic chemicals usually needed for a salt pool are salt (and you don't need expensive pool salt either--ordinary water softener pellets or solar salt works just fine), muriatic acid, stabilizer, and perhaps calcium for a plaster pool. Borates, while not needed, are highly desirable but they can be added inexpensively with plain ordinary borax and some muriatic acid.