Without heaters, we'd need ten thousand puppies to keep us warm. That sounds great, but is it?
Ten thousand puppies! Boy! Wouldn't that be great? Well, no. No, it wouldn't. Not even if you loved puppies. Because think about what ten thousand puppies would require. That's ten thousand different dishes of food, and ten thousand portions. That's ten thousand fuzzy little creatures tackling you trying to be first. That's ten thousand different barks when someone knocks on the door, unless you train them, which requires ten thousand different immediate scoldings.
Ten thousand leashes. Ten thousand collars. Ten thousand bones or chew toys. Ten thousand baths on bath day, or one thousand bath days for ten puppies at a time. Sure, you'll be snuggly on the bed for a little while, but do you have any idea how much ten thousand puppies weigh? And that's sleeping weight too, when they collapse.
Get a heater. Really. A heater and a puppy and you can enjoy a nice winter's night warm and cuddly. Without nine thousand nine hundred and ninety nine others getting in the way.