There's several problems with grappling and ground-fighting for self defense. The problem is you can't grapple and defend or strike at the same time. At least not with the techniques in many grappling arts. It's either because the rules protect you from striking or your opponent is trying to grapple anyway. Things change in a no rules environment. I sparred with my partner in a no rules sparring session. He knew he couldn't beat me in striking and kicking so he took me to the ground with primitive grappling skills via. takedown. He got in a top mount position as i struck him several times. Eventually, he pinned my arms and held me down. His face got too close to mine so i headbutted him in the nose. Luckily, it was no contact or he would've been knocked out or at least dazed to where i'd be able to escape. I gave up from exhaustion. Whether or not ground-fighting worked in this case is not the point. The fact that he took some blows before finally submitting shows it's not effective for self defense. Effective self defense is supposed to minimize damage taken and maximize damage done to your attacker. In another case, ground-fighting didn't work well. We took it to the ground. I grabbed a practice katana, drew it, and ran it through his stomach. He didn't see it coming because we were staring at each other face to face. It's why self defense instructors advise not to go to the ground.