There are strains of Ga Noi Don that have been selectively bred to not have spurs. They are traditionally used for fighting, in their home country of Vietnam. It's generally not a lethal competition, it's more of an endurance competition. It can be fatal, but usually the outcome is determined by which bird leaves the barrier that surrounds them. (which is like a foot high). This takes place in Vietnam, a match can last many hours, hence the breed's sparse feathering (very hot and humid). A bird can be valued very highly, a village champion might eat at the same table as his owner. The intensive daily handling required for conditioning forms a very special bond between these birds and their humans, thousands of years of selective breeding for this purpose has all but eliminated any traits of aggression towards human handlers. The purpose of selecting toward spurlessness was not for protecting humans, as other similar breeds that have spurs don't display any human aggression. This was done to lessen potential for injury to the birds, because those birds are so treasured, in a country that has long been impoverished by foreign and domestic conflict.
Traits like these are floating around in many game breeds. Roosters that hatch eggs, auto sexing breeds, and extremely laid back attitudes towards humans, high levels of intelligence (there are folks with birds that are basically obedience trained). But many people are so closed minded that they ignore thousands of years of selective breeding towards these traits because of the original purpose of that breeding. Unlike our savvy predessesors that recognized the potential of isolated genes, like pencilling, (which most likely came from games) and let us not forget the Asil component in the most popular broiler chicken.