OK. Thanks for all your comments. I was only comparing to other species of fish that are normally fed what they eat in nature.
Obviously discus fish keeping has developed into a completely different game. I just tried to find information about other, more natural approach but judging by the reaction on this forum, there won't be any documenting it here with the fear of being condemned.
I didn't think it would make so many people angry asking a simple question and giving the raw reason why.
By the way, there are people feeding their dogs diet that they supposedly have evolved to eat in nature. Some of these approaches are called BARF.