I think a lot of these so-called "miracle diets" tend to make the incorrect assumption that the people about to take them on come from a starting point of eating absolutely garbage.
The second false assumption is that all bodies are the same, with the exact same body chemistry, which seems unlikely to me.
In most cases, I think the "miracle" we'd be best off pursuing would be simply to not eat processed foods, to whatever extent we can. My older relatives who mostly died in their 90s in pretty good health all had in common that they ate food made from fresh ingredients, from scratch, not crap out of a box.
I tried an all plant-based diet many years ago and ended up with a moderately bad case of anemia after about six months; a week of eating fresh salmon and lean beef and I was good as new.