This is why DW tablets with "salt action" don't make much sense.

This is marketing speak, as they believe that the general populace is too
thick to realise how it works.

The tablets contain phosphates that attempt to reduce the worst effects of
hard water. However, they prefer to call this "salt action", so that people
equate it with putting salt in the softener. Of course, it can't be anywhere
near as effective as a proper ion-exchange softener, so you should continue
to put salt in the chamber.

Christian.