Apologies, this will be a little long because I want to try and make a number of points.
First...What? KM as old as karate?!?!?!?! KM basically started being developed in the 1930's by Lichtenfeld as a synergy of western boxing, wrestling and street fighting. It was basically refined into a something resembling what we call KM in the 50's and 60's when he was the chief Instructor for the IDF (as an example he didn't formally include Judo elements until the 1960s.) Then in the 1970's his chief student, forget the guys name, included Aikido elements. In the 80's they introduced Muay Thai and then BJJ techniques. Now I do not know from whence the idea of bursting came from, but it, in my experience is fairly unique. So basically the KM we know today is as old as the 1980's.
If you look at Okinawan Karate we are talking centuries old. "Japanese" Karate early 1900's. Now Kyokushin is roughly from the infant KM period (1950's) but Kyokushin is simply a "next step" in a far older art, unlike KM that synergizes from a host of source; arts you would not think are compatible (Muay Thai and Aikido), and instinctive bio-mechanics (bursting).
You also seem to make an error in think "new" means "specific technique invented in 2017." New here is about context not a calendar.
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Next, remember TMA's tend to focus on trained techniques, that take a fair amount of time to simply become competent in a real fight let alone master. The whole point of KM is that it is supposed to make a competent fighter when dealing with the time constraints of Military/Security Forces training. So the combination of seemly disparate, but basic, techniques and some "techniques" that are based on instinctive biomechanics does indeed make it "new" context wise. All the ideas in the art existed before but lets look at metals as an analogy. We had copper and tin, someone came along and combined them and we had Bronze. It was "new" but based on a combination of things we already knew about.
None of the above is to say that TMA's are bad. The problem is complicated because you seem
1. All MA's (even MMA, KM and other modern styles that try to combine the best of all) technique wise have inherent strengths and weaknesses. Sometimes it's inherent in the art, sometimes in the practitioner, sometimes a combo of all
2. TMAs as they are trained all too often have an additional weakness. The train WC vs WC, Jow Ga vs Jow Ga, BJJ vs BJJ, Muay Thai vs Muay Thai etc. This creates an additional inherent weakness.
-What does the WC guy do if the BJJ guy gets him on the ground?
-What does the BJJ guy do if the Jow Ga guy doesn't let him grapple?
-What does the Muay Thai guy do if the WC guy gets in close so kicks don't work and traps so he can't clinch and thus can't knee effectively?
-What does the Jow Ga guy do if the Muay Thai guy gets him in the clinch and the knees start flying?
Now some of us are lucky and go to a school where multiple arts are trained and thus can "test" ourselves against them. Some of us seek it out on our own
@JowGaWolf did it with his brother with Muay Thai, I spar with my TKD brother-in-law and a co-worker who is a BJJ guy. However I have never experienced being in a Muay Thai clinch and getting kneed the way
@JowGaWolf has. It would be new to me. I would have to learn if WC, Kali or Aikido has the better solution. I suspect "giving in" and going to the ground and using Kali or Aikido would be the best option but I don't know and it would be a "new" learning experience. Luckily, at best, I tend to deal with talented "street fighters" and so after 19 years of dealing with that, not much new comes along, but if it did, all my training and experience would have to adapt quickly.