Not peeing can ruin your kidneys.
We regularly transport more than one wheelchair bound person to dialysis who didn’t drink enough water.
I think the point was to pee less; not to pee not at all. Could even have an espresso... or a double even. One time I had a double espresso in Las Vegas and couldn’t sleep for nearly 24 hours. I guess they want you wide awake and pulling on that one armed bandit or something...