Body language

I’m currently reading a book which has a chapter on canine body language.

“The tail is important for both balance and signaling, which is why the practice of tail docking, or partial removal of a dog’s tail, is so harmful. Because the tail is a prime indicator of mood, dogs with docked tails are unable to communicate properly with that part of their body, meaning that other dogs and people miss vital signals.”

So if this is true, what about breeds of dogs that are born with reduced/no tails (Australian shepherds, bulldogs, corgis, etc) or those with deformed tails ?
I don’t believe my Nifty (born with a deformed tail) has ever had problems communicating with dog or human 

Do he born without tails have been deliberately bred that way - it isn't natural. Yes,there are deformities, but that happens with so many pups & not just tails.

Nifty may have a slight deformity, but she still does have a tail, doesn't she?

Yes, her tail is about a third of normal length

Yes, but she still has a tail; I think the problem can lie with a tail docked really short (boxers, for example, or Aussie Shepherds) as all it does then is wiggle.

The breeds that are normally born without a tail often have spinal problems as well.