Shared Dynamic Libraries. Not to say they aren't useful. Keeping applications small, keeping security updates simple, sub linear ram scaling, yada-yada-yada, big wins cross the board, not debating that.

The pervasive link detection structure of effectively everything on GNU/Linux assumes is (more-or-less) objectively incorrect behavior in any sane security minded context. Binaries should be able to declare the interface/contract they expect (args/types/abi/exceptions/cryptographic signatures/digests). Then the runtime linker "match" against the local system. The current system is basically 2 levels of string equality checking.

Nix goes into the right direction by getting your runtime linker/elf-runtime & package manager "integrated". But this sort of just feels like putting 'lipstick on a pig' and dancing around the core issue that `foo.exe` cannot ever realize `foobar-v1.8` and `foobar-v1.7` are both installed on the same computer. Nix just manages the environment/symlinks such that `foo.exe` doesn't realize this fact.