A large part of the current usage of the terminology comes from historical momentum. It used to be the case that transistor size was fairly well correlated with

A large part of the current usage of the terminology comes from historical momentum. It used to be the case that transistor size was fairly well correlated with performance and capability. Moore's Law was well-known and a simple transistor size was a good, easy way to approximate performance potential for power consumption, speed, capability, complexity, etc... That single number started getting slapped on all of the marketing and documentation as a somewhat useful "overall performance rating" substitute. Companies got used to showing it off. Consumers came to expect it. The real, actual usefulness of the number diminished slowly enough that it's just continued so far. And marketing doesn't like removing stuff that they think makes their products look good. It's also still useful as an identifier to distinguish between one node process and another, so it's not entirely pointless, even if the nomenclature is meaningless.