Not only that but directly under the heading "Nullifying problems with null references" they start to describe problems with global variables. The article is all over the place. There may be arguments for functional programming but I wouldn't trust this writer because their thinking is so sloppy.
Also: "But many functions have side effects that change the shared global state, giving rise to unexpected consequences.
In hardware, that doesn’t happen because the laws of physics curtail what’s possible."
The laws of physics? That's complete waffle. What happens when one device trips a circuit breaker that disables all other devices? What happens when you open the door to let the cat out but the dog gets out as well?
Also: "But many functions have side effects that change the shared global state, giving rise to unexpected consequences. In hardware, that doesn’t happen because the laws of physics curtail what’s possible."
The laws of physics? That's complete waffle. What happens when one device trips a circuit breaker that disables all other devices? What happens when you open the door to let the cat out but the dog gets out as well?