"Some no doubt are idiots. Others may have done the research and come to the conclusion that the potential risks outweigh the potential gains for their cat. "
If they are having litter after litter they are idiots. I have intact animals that will never be bred but my neighbors have intact animals and let the bitches get bred to whatever drops by and if they can't find homes for the puppies they let them roam until they are hit by cars on the highway.
Cats "queens' specifically are crazy when they come in heat and very annoying if not spayed. Stimulation to end estrus with a Q-Tip is possible but who would want to molest their cat every 3 weeks?