Wolfram is known for this. He's clearly a bright fellow but he is not even close to being the only or the first person to work on stuff like cellular automata, computational theories of physics, or complexity. He did not invent everything he claims to have invented and while he does footnote he's definitely not drawing attention to any of the others in the area.

It's tragic really. A New Kind of Science is full of brilliant ideas but the narcissism that drips from every page ruins it and probably prevents some of these ideas from getting the reception they deserve.