I wouldn't go that far. As far as D&D goes, I agree with myself, quoting Jon Peterson-
"...Gygax and Arneson were co-creators of D&D, in at least the crucial sense that Gygax would never have worked toward such a game without incorporation of Arneson's vision, and Arneson would never have realized the publication of such a game without the structure that Gygax provided it." That sums my opinion up. D&D would not have happened absent either of them.
But yeah ... I've known many people like Arneson in my life. Great as friends- never, ever, ever get into business with them. From everything I've read & heard, he was a wonderful person if he was DMing your game, and a terrible person if you were depending on him for something important.