You are taliking in test conditions, not in real world. The test conditions are carefully set up to not introduce ground noise. In the absense of ground noise, the only benefit of balanced comes from a higher SNR resulting - typically - from the higher output voltage.Still, in real world we rarely see more than a couple of db improvement with balanced vs single ended signals. And very often there is no improvement at all... even the opposite in poorly designed circuits.
Theory is correct, implementation is another story.
However ground noise is sometimes very difficult to eliminate in real world setups, as evidenced by the number of posts we get here asking how to eliminate hum/hiss. Note this is a system problem, not a device problem, and all my statements were referring to system SNR, and included the phrase "when ground noise dominated"