Why? Because it would need to be able to run on all possible future hardware, regardless of whether that hardware is aware of needing to be backward compatible with anything. The code would need to somehow be able to look at its hardware environment and modify itself to be able to communicate and fulfill its purpose within that environment, even if that environment is some kind of mushroom from an exoplanet three galaxies away. NP-completeness would be this thing's first trick, and it's arguably a form of mind control.
I mean, that's obviously stupid, and I'm obviously drunk, but be careful with the word "universal."