Nobody is recommending OP solely drink soda for hydration. The point was just that caffeine is not a real issue for hydration.

If we’re going to give safety warnings for caffeinated drinks–as though OP were unaware that caffeine over consumption is not magically avoided if you’re trying to hydrate–let’s also advise them to take reasonably sized sips so they don’t choke and to drink from clean containers so they don’t get sick.

If you’re reading this OP, virtually everything you drink is hydrating. Milk. Coffee. Soda. Juice. Tea. If you’re chugging oil-based liquids, those aren’t hydrating. But I’m guessing they aren’t a major part of your diet.