I was about to write "you are right", but then realized the question might be a bit more complicated.
Some of the big breweries use a technique of fermenting a stronger "concentrated" beer which is then diluted to proper strength for packaging. The stated rational is that it has more body when done that way than if it was fermented with all the water present. Not sure if that is real or marketing mumbo jumbo to justify an economic advantage: make more beer per batch than your tank can hold.
I've tried the technique, and I can't say if the body really does come out better like that, but it certainly doesn't hurt anything. Provided you deoxiginate the water before mixing it in. But that is easy, just boil it and let it cool before using it.