I can't believe that no one's discovered this yet. Maybe this is a manifestation of the Python paradox. The kind of people using the jar command (Java developers) are the kind of people who just accept the limitations of their systems without questioning.
Your argument is pretentious, arrogant, and ultimately clueless.
For small builds, jar is sufficiently fast as to not raise any red flags. For large builds, jar overhead is small enough as to be easily lost in the noise.
The build should have been profiled, and this is an embarrassing bug, but it's absolutely, completely ridiculous to generalize this to the fact that Java developers could be the "kind of people who just accept the limitations of their systems without questioning".