All devices have different ranges of color they can reproduce and nothing can produce the full CIE colorspace. Even if we possessed a device with that capability, we lack the ability to describe all possible colors to that device. AdobeRGB and sRGB are subsets of CIE and computer monitor makers struggle to make professional grade monitors that can cover 90%-100% of those gamut ranges.

The Pantone system is constrained further by just being a subset of colors exist within a limited gamut range. Pantone colors are only ones that can be produced by the mixing of, I think, 14 base colors. Their system sets clear limits on the scope of the problem and provides clear and consistent reference points.