On Heat

So in TLA we saw Sozin bending the heat away from a volcano. We also nigh-always see a waterbender turning water to and from ice.

Doesn't this mean Firebenders and Waterbenders have some indirect control over Heat? If so, wouldn't that be horrifying? To just draw all of a person's body heat out and let them die of hypothermia any time?

It would be Firebending's near-equivalent to Bloodbending. Draw out all of a person's heat from their body and watch all their bodily systems shut down

... I'm going to go sit in the sun for a bit.