> This nuance is something that only the nix model started to capture at all.

Unpopular opinion, loosely held: the whole attempt to share any dependencies at all is the source of evil.

If you imagine the absolute worst case scenario that every program shipped all of its dependencies and nothing was shared then the end result would be… a few gigabytes of duplicated data? Which could plausible be deduped at the filesystem level rather than build or deployment layer?

Feels like a big waste of time. Maybe it mattered in the 70s. But that was a long, long time ago.