The strengths of MMA for real combat are many. First of all MMA, includes both striking and grappling, two of the most important elements of a real fight. Most combat sports focus on only one or the other and are quite limited in what types of attacks are allowed. For example, wrestling allows takedowns and pins, but no submissions. Boxing allows legal punches, but prohibits kicks, knees or elbows. Judo only allows throws. Muay Thai allows grappling and striking from the standing position, but not on the ground. MMA, on the other hand, allows all of these important elements of combat, making it a much more well-rounded discipline. Both striking and grappling take place while standing and on the ground. Submissions, holds, and chokes are also allowed while standing and on the ground. All types of throws and takedowns are allowed. However, each venue in MMA is slightly different, and certain strikes and submissions are disallowed depending on the show.
Before the first Ultimate Fighting Championship and for years afterward, there was a big debate among martial artists asking "what's more effective: grappling or striking?" This is a ridiculous question. This is the equivalent of asking, "Is it better to pass the ball or run the ball?" in American Football. Or of the military, "What's better, the Air Force or the Navy?" The answer is that it depends on the situation and you obviously need both. The modern MMA fighter obviously has a good handle on both striking and grappling, and this debate has finally begun to fade away.
Today, MMA is the fastest growing sport out there. It seems that everyone is getting involved with the sport either actively or as a spectator. In today's environment, anyone who's serious about learning to defend oneself must learn the fundamentals of MMA precisely because everyone else is doing it. In combat, it's the unfamiliar that is the most dangerous. For this reason, it's essential to educate oneself on MMA. Everyone who's serious about learning to fight should learn both striking and grappling and have MMA experience as a base to work from.
With that said, we need to keep in mind that a street fight is very different from a cage fight. First of all, street fights are rarely one-on-one. Many fights start as a one-on-one conflict but quickly become a multiple opponent situation. Many MMA fighters have the grappling mindset and are inclined to take their opponent to the ground, where they prefer to fight. This will immediately put you in eminent danger in a multiple-opponent fight. Every grappling position on the ground will put you in jeopardy of being kicked or kneed in the head if you're fighting more than one opponent. However, should you be taken down in a multiple opponent fight, you need to know ground fighting in order to escape the situation. A common slogan among Jiu Jitsu practitioners is that "most fights end up on the ground". While this may be true, most fights involve a weapon and multiple opponents.
In addition, street fights rarely take place on a soft floor. This changes everything for the grappler. Often times, the ground is rough with rocks, gravel, or even broken glass. Asphalt or concrete surfaces are far from ideal for grappling. Even the superior grappling positions with the possible exception of "knee on the stomach" hurt when rolling around on the ground. Even many of the takedowns in MMA, such as double and single leg tackles, involve dropping a knee to the ground, which can shatter a kneecap.
A related point is the wearing of shoes in the street. It's important to feel comfortable fighting with and without shoes on. Even many strikers, like Muay Thai fighters for example, have never trained with shoes on. Another thing to keep in mind is that shoes can also be used effectively as weapons to make kicks more effective. More types of kicks become effective when a shoe or a boot is worn.
Let's assume that a street fight breaks out on a soft floor and that it's a one-on-one fight. Remember this is not a gentlemen's grappling game. The individual who's willing to take the fight to the next level, and knows how to, will often win. Finger locks and breaks, for example, can completely change the game. In the old Catch Wrestling days, many fights were won with broken fingers and / or missing eyes. A grappler who knows how to use a barrage of bites, pressure point strikes, elbow digs, fish hooks, hair pulls, eye gouges, groin strikes and head butts on the ground (along with the more conventional strikes and submissions) is a whole other animal.
These elements come into play from the standing position as well and are a big part of the training in Jeet Kune Do and Filipino Kali Silat. Bruce Lee was said to have been incredibly effective with a finger jab to the eyes from any angle. Anyone who watches MMA knows how effective even an accidental eye gouge can be. For example, Mirko CroCop defeated Mustapha Al-Turk with an eye gouge in UFC 99. BJ Pen and Chuck Liddell have unintentionally or intentionally used the eye gouge to help win UFC bouts as well.
The other obvious element of street fighting and self-defense that's missing in MMA is weapons training. Real fights involve weapons. If push comes to shove and it's time to defend loved ones, it's natural that most will pick up some type of weapon. Man has used weapons to defend himself from both man and beast since the beginning of time. In many third world countries, most everyone carries a weapon all the time. It would be ridiculous to train mostly in grappling and kickboxing where everyone carries a weapon and they're not afraid to use it. According to police reports nation wide, by far the majority of assaults in America involve a deadly weapon. Furthermore, should you ever end up in the prison system, practically every fight involves a makeshift edged weapon.
Real combat (wars) have always involved weapons and always will. MMA fighters like to compare themselves to modern gladiators. While modern MMA may be one of the closest combat sports to what the gladiators did in ancient Rome, the obvious difference is that gladiators fought with weapons. What most people don't understand is the big difference between a weapons expert and someone with no training. It's exactly like Jiu Jitsu or Muay Thai in that a skilled practitioner of knife or stick fighting can dominate a novice. The response to this is often that "I'll just get a gun." The question then becomes, how much training with a gun have you done?
Firearms training is another important element of real self-defense. Many martial artists neglect this important part of martial arts training. The unfortunate truth is that in a street fight setting a gun can often come into play. Even "road rage" sometimes develops into a situation where an infuriated individual wields a gun. It's important to keep in mind however, that guns can jam or run out of bullets and are not a good choice for close-range combat. A knife is much more effective at close range, and will never jam or run out of bullets. Most everyone in the martial arts community knows that the Filipino Martial Arts of Kali and Escrima are the best arts for knife and stick fighting. What they often don't know is that Kali practitioners learn to fight with anything they pick up. Even firearms training is an important element of Filipino Kali.
In conclusion, MMA is the most complete modern combat sport. Any self-defense or martial arts program that's missing MMA training is missing a major element of real fighting. Mixed Martial Arts has proven that being a well-rounded and complete fighter involves cross-training. All MMA fighters understand this. There is no single martial art that has everything needed to be a successful MMA fighter, even within the limits set by the rules. Once the rules have been removed, as in a street fight, many more elements and skill sets come into play. Preparation for street-fighting and real-world self-defense requires even more cross-training than MMA in order to be truly prepared.