> I am a little confused as to why toy breeds should be older when they go to their new homes
Apart from the fact that the breed club would come down on you like a ton of bricks?
Have you ever seen a 2oz newborn puppy? There is no comparison, and they are very delicate. Wouldn't take much to step backwards and crunch one underfoot. You really need to be extra careful, and no way can people comprehend when they want a Chihuahua or Papillon when they've always had a goldie/lab/shepherd etc.
I had one lady desperate for a Chi pup, and, insisting that all the family come as is normal, I had to refuse. Husband sneeringly said "Well I can't mess about watching where I step." You have to lift them up if you want them on the sofa. But letting them jump off can be disaster. It is normal for my bitches to give pups a comfort suckle at 12 weeks when pups leave home. They do nurse for a lot longer than large breeds. It isn't unusual for Chi pups to weigh 500gm at 10 weeks of age.
I could go on and on. But it's so difficult to explain when you've never seen how little these tiny guys are. They are not for everyone that's for sure.