I partially agree with you, to keep a shiny health people should eat everything, we are omnivorous after all. But the definition of superfood (which is not scientific, but just a commercial one) just defines something with a greater nutrition value among same types of food and not a food that can give you all kinds of nutrients. About this, let me say that summer is approaching and we often see some diets to lose weight that include just 1 or 2 types of food: these kind of approaches are totally unhealthy and even dangerous for some people. There is no food that can give you anything our body needs, as you said, but lots of food can help our body to work better. Dark chocolate, in small portion, is one of them!

One last thing about scientific researches: it's true, sometimes they say "white" and other times they say "black", making things confusing. The thing is, some researchers are sponsored by companies and so they are heavily biased. This is where real professionals come in to play, studying, reviewing and comparing papers to share the real evidence. Don't be so distrustful about science and research, there are lot of people out there (still the majority, I can assure you) that study and work to produce scientific research that are good for the human kind and not for their pocket!