There are so many misconceptions on this subject. There is a tremendous difference between developing a martial art skill, and developing self-defense skill. These concepts are not necessarily mutually exclusive, but they are quite different.
A well rounded martial artist with an understanding of what is at stake in physical confrontations...as well as an attitude of survival rather than victory...can be incredibly effective at self-defense. The problem is that his or her skillset requires years of training and dedication, and the person will probably spend a lot of time developing skills that are useless in a life-or-death struggle.
In my experience, a person that has survived a genuine assault, regardless of "winning" or "losing", will not brag or boast. The event is traumatic and unsettling regardless of outcome, and is recalled reluctantly. A mutually aggressive 'shoving match'-turned 'boxing match'--while potentially dangerous--is entered willingly by both participants. This type of fight has no place in self-defense discussions. Nothing justifies engaging in physical conflict except for grave necessity.
Consider this: Fighting is like shooting. It is only to be done in a situation that is life threatening, and should be done as a last resort. De-escalation did not work, walking away is not an option, and this person means to harm me or worse. Now...I may fight.
The good news is, if this is my mindset and I always adhere to it, I may focus all of my attention on moves and tactics that actually work. They are the most effective, deceptive, instinctive, and lethal moves that can be taught. But what choice do I have? If I am to develop skills that lead to survival, the answer is-None.
Students in my class will understand this, because an efficient, preemptive eye strike (finger fan) is the primary weapon in PSP's arsenal. Distract, divert, then strike. Stomp the knee, chop the throat, slap the ear...these moves permanently damage opponents...but they work. If I am compelled to fight through no fault of my own, then I am free to do what I need to do.
I used to teach martial arts. I still train in martial arts. I absolutely LOVE martial arts, in fact. Yet life experience, interviewing those close to violence, and years of study and practice have taught me some stark lessons on the subject. There is no need to re-invent the wheel. Chat with both types of instructor, assess your needs, and make a choice for yourself.