Things like inclusion and other theories such as the one you describe are only possible in rich and technology-advanced societies. And are vulnerable to groups chosing to play against the whole society.

When you have to struggle for life, discriminating against some categories, such as disabled people is necessary for the whole group to survive. Animals do it, and humans in antiquity did it too, out of necessity. It's actually how evolution happens. Humans still do it to some extent when they choose how to mate : they discriminate.