I have ideas on this subject based on research and common sense. I became interested in why people mix different breeds when I bought eleven chicks from a personal person unknown to me and discovered later that my chicks were not what they were sold as. Then I wondered, what was the purpose of mixed breeds of chickens. I discovered that some people mix two breeds together: in an attempt to make a new breed, to try and get different or certain colored eggs, to improve the outcome of the purpose of a breed in different climates, taste, and strengths, because some people just let different breeds run together, and for beauty.
What breed am I? The picture above is a mixed breed chicken that is now a hybird. He is my favorite rooster because of his lovely blue colored feathers and his perfectly shaped beautiful comb. I was told that he is a Blue Wyandotte a new kind of Wyandotte that hatcheries have discovered. He appears more stately and slender than a Wyandotte to me.