I'm not an urban planning expert, but what I think it means is that the general RCI relationship zoning (common in America) has been a main staple for city builders since the first SimCity. Long long ago, as industry started to become more of a common thing in a town, it ran into the problem of pollution and other problems due to industry and residential being in the same area. One of the main characteristics of American city zoning is dividing up the main 3, Residential, Commerical, and Industrial, to improve health and keep people from living nearby dirty areas.
From a gameplay perspective, having those 3 main variables as things a player has to balance is a pretty straightforward and easy to understand mechanic, especially back in the days of SimCity 1.
USA urban planning also has a history of greater car usage due to this as well as other factors like interstate systems. The European model is more conducive to mixed use zoning and such, but is harder to distill into a simple and fun gameplay mechanic.
After all, we are playing a game, first and foremost.