"You can't build anything with five hex codes. To build something real, you need a much more comprehensive set of colors to choose from"
The website color pallet is more involved than a simple collection of 5 hex values. In reality, each of those 5 values needs between 2-5 additional saturation values in order to serve as accent colors, highlights, warnings, promotions, and alerts.
The five base colors simply serve as the pallet, but in reality, approximately 16 colors are needed to comprise the full pallet.