They likely don't know of the prior art. In fairness "one thing per page" isn't a very literature searchable topic and many people have trouble finding good search terms to uncover all the relevant prior art. "Wizard" doesn't intuitively scream out "one thing per page".

I have no idea how prominent IBM wizards are in the design literature, but I'm a scientist and I can speak to the challenges of finding relevant literature when all you have is what search terms makes sense to you.