I'm guessing you're referring to information like this:
What do you mean by "has worked" for so many athletes in the past? Do you mean there are athletes who perform 200+ crunches a day and still perform exceptionally? This is the same logic behind naysayers of say the effectiveness of low-carb dieting based solely on the fact that there are lean muscular people who eat lots of carbs.
The popular question you are bringing up here seems to be--are these fighters improving performance by doing conventional ab exercises, or IN SPITE of them. In fact, I believe Robertson would go as far as to say they are hindering their performance.
Personally, I get behind what Robertson's advocating here, and pretty much have since I began seriously training. It was very easy for me to part ways with crunches for a few reasons:
Like you, I would need to do 200+ crunches/day just to feel anything. With something like pallof press, or landmines, I can do 3 sets of 10 and be on my merry way.
I found it difficult to progress with crunches. To a point, you can add weight, but then it just reaches a point of putting your body in an awkward position to keep adding. With the exercises he listed in that article, the progression is as natural as adding weight to your squats.
So I'm not a trainer/therapist/any kind of expert, and can't really defend what's written in the article without sounding like an amateur by basically repeating everything it says. For me, it's a matter of: they're not worth the risk. My humble opinion.