There's 4 diets. If there's zero correlation between your blood type and which of those diets is best for you, there's still a 1 in 4 chance that your blood type will match the best diet (of the 4) for you. This does not depend on the complexity of the diets.
That's where I didn't really focus in, Mostly focused on what's recommended & what's to avoid for all blood types. Then obviously some confirmation bias after my elimination diets/ intuitive eating. But yeah I didn't realize some people are probably following it to the letter for their blood types without confirming with how they feel / placebo / going from a shitty diet to only whole foods.