Unnecessary, cultish, and yet another diet that supposedly cures nearly all ills.
But what if it did in fact cure their ailments?
There are 3 explainations, the first two are guilty of reductio ad absurdum and lazy thinking imo.
1) 100% placebo, which can be a very powerful force of nature.
2) The "elimination" diet aspect cut out pro-inflammatory foods and other unhealthy bullcrap like sugar, seed oils, trans fats, and all other processed garbage.
3) Everyone has different genetics, biochemistry, gut biomes, etc and some can genuinely benefit from diets that others would not, which explains why some people have benefit from carnivore, others have benefit from vegan, etc. No two bodies are the same.
I'm inclined to go with 3, but given that this would introduce an insane amount of complexity to the health industry, no one wants to open that door since diet advice has to have mass-market appeal, it needs to be a packaged one-size fits all approach that is easily sold, instead of tailoring (which requires the individual to experiment themselves). For this reason I do think anyone who promotes the carnivore diet is guilty too, you shouldn't promote any type of diet, instead just bring awareness that it's an option.
I cannot rule out the elimination diet or placebo, and maybe it's an element, but you gotta ask yourself how someone can eat nothing but meat for years and feel great, this runs counter to so much of what we hear, this should result in all sorts of ill health consequences and death according to what we hear from the mainstream. So I think this warrants more investigation. But we haven't done real food studies in decades, the kind where you have individuals on a controlled type of diet for years and years and observe them. All diet related "science" today is based around self reported surveys and correlations, that's not real science.