Your last sentence is just wrong. Pantone encodes thousands of colors. RGB/CMYK can encode references to as many (within-gamut, but you can also hack around this) colors as you want, typically millions, often billions.
Sure, you might not get Pantone 123 if somebody asks for #ffc72b. But if somebody says "use Pantone colors only" and specifies #ffc72b, you're going to get Pantone 123.
