Bad premise and bad conclusion.

Your urologist will not tell you to drink eight cups of water a day. Rather, your urologist will tell you to drink enough water to *pee* eight cups (about two liters) of water a day.

Depending on what you're doing, that could be a little or a lot. And when it's a lot, the thirst mechanism doesn't always work so reliably.

Inadequate hydration over a prolonged period of hot and muggy weather led to me getting kidney stones later on. Not fun. And unless medical evidence is wrong about preventing future kidney stones, the "drink when your thirsty" strategy will not have me hydrated enough.

Sure, for the limited situation he was describing, maybe the dehydration obsession is misplaced, but this was an oversimplified topic to the point of being meaningless or even dangerous to some. Adam certainly ruined something today.