And it was always pretty minimal benefit. Depended on the exact same version of the library being cached from the same CDN... in the days of jquery hegemony, maybe jquery cache hits could be a thing, but even that was probably minimal. These days JS usage is much more diverse.

It was like an idea people had that this would be a cache benefit, but just theory not actually from real-world observation. I recall several people trying to do investigations to determine how often cache hits would happen in these cases, and finding it wasn't that often after all in real-world use. But I can't find em now, google is crowded out by people talking about what you link to above!