Used Code Of Spectral Tiger Why Colour Code Is Used To Display The Values Of Carbon Resistances?

Why colour code is used to display the values of carbon resistances? - used code of spectral tiger

My question is why the color coding is designed to show / express the numerical values of carbon resistors? I mean, why simple figures like 100, 2000 or 5500, etc. are not used for this purpose? What are the advantages of using this code instead of numbers?