Do Combat Sports Prepare One For Self Defense?

I just read a blog post by a "Self Defense Expert" saying that competition does not prepare one for real fights. These experts usually get into this mindset philosophy and the chaos and unpredictibility of "reality". If you will look into the backgrounds of this experts, you will see that they never have any combat sports experience. Sure combat sports have rules and a Ref to prevent one from being seriously hurt. But, the intensity, the pain, the fatigue, the risk of injury are all there. A resisting, non-compliant opponent is there. Feedback of whether your technique works or not is there. No training drill, fight simulation, mental training can prepare you for real fights. So, the next best thing is combat sports.