I'm not Dr Menzies, but I'm going to answer anyway with "hello, because we need salt!"

Refined sugar = bad
BUT sugar in whole fruits & veg, in the right quantity for your particular needs = good

Canola oil, margarine, trans fats = Bad, naughty fats
BUT stable animal fats, coconut oil, extra virgin olive oil, whole nuts and avocado = good, healthy come-to-mama fats

Refined salt in processed foods = probably bad
BUT real salt is VITAL for a lot of the ways our bodies work
So cutting out the salt in processed foods is a good thing, but not eating salt at all isn't

Now that I start blathering on, I remember I wrote a post about salt, once upon a time

https://steemit.com/food/@kiwideb/the-sorry-story-of-salt-and-how-we-got-fooled-again