This is still relevant in today. Not only are there non-color e-ink devices like the Kindle but there are accessibility features in macOS and Windows to change or remove colors from the interface. One of the Web Content Accessibility Guidelines (which are useful in non-web cases) is 1.4.1 Use of Color: “Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element.”
Also, designers shouldn’t get too wedded to colors, clients and other non-designers love to weigh in on them, “does it have to be so blue?” or “we’ve changed our corporate branding color scheme, this design needs to use them.”