So how was that for you? You have run head long into a big difference in the way humans communicate and the way dogs communicate. We have words, languages, punctuation, antonyms, synonyms, slang, accents, and other ways we verbally communicate. Multiple people can look at the same thing and describe it using different words and we all can understand exactly what that thing might look like.
Our dog does not have the multiple communication choices that we have. He does not have a dictionary where the same word might have multiple meanings and a list of other words that mean the same thing. All he has are the sounds and tones that come out of his mouth. We might call it whining, growling, or barking. Those are all the tools that he has when he wants to verbally communicate to other animals.
That is how our dog verbally communicates. If we want to have our dog sit, we must have a unique sound that whenever he hears it, he always sits. Most people use "Sit". And, by the way, "Sit, sit, sit, sit" is a different sound than “sit”.