All martial arts tout themselves as self-defense systems. They are not means of war. War is group against group and always employs the latest advancements. If you want to learn warfare, join the Marines or some other branch of the services. Learn how to call in a drone strike.
Self-defense is a personal issue, perhaps extended to family and friends. It is about a localized conflict involving very low numbers, most often one-on-one.
Over the decades, some martial arts have regulated themselves into sports. With regulation, the techniques change to fit the rules and conditions. Raw self-defense techniques that work perfectly well may not be possible with a set of boxing gloves on. Techniques are whittled down to what is legal for the sport, play, or training aspect of the game. If you want to win the game, get best at the things allowed. Loss by disqualification has no honor.
However, you cannot be disqualified on the street. There are no referees, no fans, and no rules. If a thumb in the eye will save your skin, then poke it. If a bite on the hand will set you free, bite to the bone.
It is difficult to assess if a martial art has maintained its street worthiness. In a general sense, all of them are useful. Training, conditioning, and at least some discussion about awareness and conditions improve your odds.
Are competitions a big part of an art or style? If so, they train for rules, but that should not be the reason to exclude the art. If it entices you, if it feels right, it will have benefits. If an art or system seems to have no competitive contests it may be more street-combat oriented, but that does not mean it is truly combat ready. Instruction and attention to detail, or lack thereof, may make it unwieldy in real world, stress-filled situations. The style may spend 80 percent of its time with a weapon – one you are not likely to have in hand when the mugger shows up. Again, that does not make it useless. If it thrills you and fuels your desire to train, go with it. Eye-hand coordination is always a plus.
On the flipside, some truly self-defense arts seem filled with meaningless drills and forms. However, repetition is the mother of application. Quick responses with structure grow out of thousands of repeats of the smallest parts. Wax on wax off over and again. Do not let the form and flourish leave you thinking it is not a practical and tactical art.