Traditionally, when a new instructor did not want to be bound to the restriction of his previous organization whether political, difference of opinions beliefs, and the lack of willingness to pay dues or share the income, the solution was a change of the style name.This might be one part of the cause.
There is another issue with Krav Maga. While in the last 20 years Krav Maga was spread in the world by few large civilian organizations, the irony was that the popularity was stressed much on the reputation of the IDF as a fighting army.
While here and there former trained martial artists won local sports competition in mma, Muai Thai, Boxing and other, yet the majority of the world accepted the name of the IDF, and some parts of the world developed demand to any export that came from Israel.
When Immi left the IDF he opened his first schools in Tel Aviv and Natanyah. He decided to "make Krav Maga Suitable to be taught to youngsters" basically mirroring the Dojo marketing system, and training system.
Immi had civilian students that after about 5 years became "Black Belts in Krav Maga". In years to come the First Krav Maga association was created, and not long after, differences of opinions and lack of agreements in running it split it.
As Immi got older, he was in a hurry to see the fruit of his Genius Masterpiece. He wanted the whole world to benefit of it. Being in a hurry, he was taking large short cuts and making it easier to foreign students to quickly get teaching degrees in Krav Maga that amounted to a civilian Black Belt degrees.
Eli Avikzar was Immi's heir in the Israel Defense Force. So while many of Immi's civilian black belts did not know what Israel Defense Force Krav Maga was, Eli knew all about it.
Of course other issues such as Instructors and Black Belts thought that they were more senior than others and they all tried their best to get promoted, and Immi was a man of political peace and he tried to agree with all of them.
Then many civilian associations were created. Years later, many Israeli Martial Artists that started with the exotic names of the Orient of Karate, Judo, Jujitsu, Aikido, Ninjutsu, Kung Fu, Kyokushin Karate, GojuRyu, Shotokan and others found Immi's death as the perfect time to take pride of their Israeli heritage, and thought to take a ride on the reputation of Krav Maga.
Since Krav Maga in Hebrew translates to Contact Combat, and since Immi was dead, they felt it is the perfect time to switch.
Some took the time to learn a little Krav Maga or as much as they could, and some did not.
Over the history of martial arts, people learned from each other. uThey adopted various techniques that they felt would supplement their training and skills.
Wrestling techniques, transformed to a more "civil" fighting like the Judo where you could only grab your opponent's Gi (appeared to be cleaner, as it absorbs the sweat)and back to MMA later on and others. When students spent some time learning a Martial Art and switched, they tended to connect the dots and fill in the gaps of the lessons that they have missed.
At times, they came up with an improved method of fighting, and at times they lost the advantage of the lesson they missed.
Various Instructors at various intelligence level, and don't get me wrong, I am not getting petty over here, but what I mean is that people that made assumption using the knowledge and experiences they had and promoted themselves partially or truly believing in themselves, had gaps of various sizes and filled them to the best of their ability.
The obvious facts that sticks out are how come a former boxing and wrestling champion trained in Jujitsu as well, extracted most of the traditional training systems, creating Krav Maga. In addition, how come Eli Avikzar, trained in Aikido and Judo after he was trained in Krav Maga extracted all the long evasive motion of Aikido(tai sabaki) kept the leverages and applied the elements of Uyeshiba Laws of the Universe to a practical use with the Krav Maga principles based on Immi's theory.