My understanding had been that you get a double whammy of there being too many versions of the “common” dependencies, so it is already in-effect a per-site cache (or nearly so), but that uniqueness also means a fingerprint can be established with fairly few latency tests
While this won't improve load times, it can save bandwidth, improving user experience on slow connections. And most popular hand-selected library versions can get preloaded by the browser itself and listed as exceptions with zero added latency.
Also, this way the networking telemetry would gain a meaningful purpose for end users, not just developers.