Hi Jordan, and welcome to the forum...
I agree with you to some extent, not not necessarily completely. I live in Miami, Florida. Right now, it's about 90 degrees outside with very high humidity. An 18 hole round in our conditions is not a healthy activity without protecting yourself from the loss of electrolytes.
A person in good health would still take enough time to recover naturally that their 4 hour round outside in this heat would make them sluggish for the rest of the day. Water by itself helps, but it doesn't replace the minerals and electrolytes you lose through sweat.
And Miami is certainly not the only humid place in the world.
An aside to all this... I'm diabetic, so just sweating heavily outside lowers my blood sugar. A Powerade, (my preference), helps keep my sugar stable. If my sugar is bouncing around too much, my ability to control my body and play well decreases. These drinks also help me in that regard.
Again, welcome to the forum.