Same packed executable able to run on wide range of Linux distribution no matter what libraries installed.
Executable packed on x86 able to run on x86_64 system without 32-bit compatibility libraries installed.
There are executables packed on RedHat 7.3 x86 that run on Fedora 8 x86_64.
Because all libraries are packed there is no way those application can be broken by host's libraries update.
It's simple - to pack executable no source code (and build tool chain) required.