It has some grains of truth but it's mingled with too much personal opinion.

There are studies on how much water humans really need. If you want to calculate it the scientific way, you need to factor in at least lean muscle mass, total mass, surface area, ambient temperature and humidity, activity levels, and diet. There's no magic number of ounces that's correct for everyone.

Fortunately we've evolved a really awesome mechanism. When your body needs more water, you get thirsty.

So if you want to stay properly hydrated, drink whenever you feel even a little thirsty.