They are freaking crazy.
There's a TV in my office now, please shut it off.
I just watched a commercial where some 10 year old girl is like, "Wait, if we're losing water, why not just drink water?!"
That's why you're 10 years old, kid. You don't know @^*%.
And her mom, typical brainless soccer mom, "OH! GOOD IDEA! ARTIFICIAL COLORS AND CHEMICALS, HOW HORRIBLE!" and gets the water.
Then the announcer starts talking about how "nothing hydrates like water."
Well, that's technically true. Nothing is quite as dangerous and potentially fatal as water. Or as hard to swallow down, for that matter. I haven't encountered much that my body will actually resist ingesting when I'm desperately thirsty. Soda, I like soda, but yeah that's going to go into the "worse" bin; carbonated water is bad.
We have all these electrolyte drinks, sports drinks with sugar, and the like. There is a reason for this. When you sweat, you lose salt. You lose sodium. You burn through magnesium and potassium and calcium to run your heart.
When I bike, my sweat sometimes drips in my mouth by some magic. The stuff running down my face is more toxic than the Dead Sea; the salt content is enough that a drop of sweat landing on my tongue is literally painful, to a small degree, and even will irritate my eyes. I guzzle electrolyte water, which of course probably elevates me beyond what I need; it doesn't matter, it comes out. If it dries on my skin, sometimes I find I'm all gritty and grimy and dry, like I'm dusted with salt. I have a coworker that sweats and as it dries it turns white because of the salt content of his sweat.
If you don't replace the electrolytes, you will die. For little kids on soccer teams, this isn't much of a problem. Gatorade was invented for a high school football team by a biologist who was doing performance tuning; the worst you get forcing water into 10 year olds is 10 year olds that run themselves ragged and maybe get a few more injuries, possibly serious ones, due to fatigue and mistakes (like tripping over your own foot and spraining an ankle). They will do far better on something like Gatorade or Power Aid--which supply electrolytes and sugar--or Nuun or Zim or whatnot--which bypass the sugar, although sugar is good. Some amateurs have found that water isn't helping when they're horribly sore and beaten, and then they eat a potato chip and it's like they just met God.
If you're running a marathon or you're biking hundreds of miles and you're guzzling water like crazy, eventually you'll remove enough salt that your brain swells up from water absorption into the cells and you die. This was a big thing decades ago, before we figured out water is really bad for you.
I don't get it. Somehow we figured out that eating bricks of salt is a horrible idea (maybe because it's painful and causes your skin to peel), but it's still "common knowledge" that water is "the best thing to drink when you're dehydrated." Pure water has the worst absorption rate of anything else in water; if you drink 3L of water at once every hour, you'll piss clear, almost pure water after a few bathroom trips--if you don't die first. It runs right through your body, gets into your blood, gets sucked up by the kidneys and dumped into the bladder. If you drink fast enough, you water down your blood and die. And even then, a good remedy for constipation is (get this) drinking a lot of extra water, as it'll soften ... yeah, okay, it goes in one end and comes out the other, you can give yourself diarrhea doing this.
Sometimes I wonder if the people writing these ads believe their own bull****. Sometimes I wonder how the public actually takes the bait on this ****, because you meet all kinds of die-hard runners and cyclists that won't touch "that chemical water stuff" and only drink bottled municipality water (i.e. Dasani, bottled tap water).
Then again, Coca-Cola is pretty popular among professional cyclists these days. No joke, they carry a bottle of coke as an "energy shot" type drink while cycling. Sugar, water, cherry. Cherry Coke! What the hell?