Paying attention to rules--then discarding them--could be the key to basic self-defense.
For example, look closely at the rules of boxing, wrestling, tournament sparring, MMA, judo, and grappling. Some of these have a lot of rules, some have less. But the crucial aspect is that they all have guidelines in order to protect those involved in the match.
When I watch MMA, for example, I like to imagine how I would get free of someone's ground attack if I were truly pinned. So I look at the rules. No eye-gouging, no groin attacks, no finger breaks or wind pipe strikes. Why? Because they work--too well.
I am not saying a good triangle choke wouldn't be effective if an attacker held you on the ground, however, it might be the more difficult technique to attempt and it would take more practice, knowledge, and appropriate conditions to accomplish.
You want to get out of the situation--fast--and not leave yourself to vulnerable to an attack from any of the current assailant's friends.
Same thing goes for judo. I like judo, a lot. But there is a reason why a competition throw isn't executed after a strike to the solar plexus--it causes damage, and judo is a sport, after all.
Again, each sport has it's real world value--for sure--but often the simple and dirty stuff is just easier to teach and quicker to execute.
But then, an attacker obeys no rules either.