Back to the topic, if I may. To be sure, there are many variables and overlaps in the self defense efficacy of this or that martial art, and their approach in training. Sparring (sport) has been said to be the only, or at least the best, way to prepare oneself for real combat. I think it is very useful in developing tactical thinking, reaction speed, ability to somewhat handle stress and resistance, and in getting used to bodily contact, all without killing the opponent. That said, it is not the full solution.
Sparring is by definition a back-and-forth affair, with rule, point, and time constraints. In this respect, it can be called a game. Some rules are in place, not only to protect the fighters, but to encourage entertainment value. TKD scoring, for example, puts higher value on spinning jump kicks to the head. But those are riskier moves one may not want to attempt in actual combat. They are impressive to watch, though. Not so true of a close range upward elbow which may hard to see in the flurry of combat. Such a move can be devastating and be of more practical use, like a stomp to the knee which is not even allowed in sport.
We can contrast sport sparring with two person drills. The latter were the main method of training before MA was sport, designed solely to prepare oneself for actual combat. We should remember those early karate men whose vocation was security agents against bandits and pirates, law enforcement, or royal bodyguards. Quick incapacitation of the opponent was the only goal.
Two approaches with their own tactics, two desired outcomes, although as I mentioned, there is overlap. Each has its good points. Can you be victorious in real combat just training one or the other. I think, yes, but neither is guaranteed. These days, IMO, it is practical to combine the two training methods, along with all the other types of training like strength, cardio, body hardening, de-escalation, etc. The ratio of time spent in these several areas depends on the person's goals in training MA, as well as their individual natural attributes.