Look what poor power does to a computer. Why do companies install all kind of power equipment to keep their computers in top form, if it really does not matter?
Would you trust a hospital if they did not control the quality of the power running the machine keeping you or a loved one alive while they are getting well? Would you be happy if they said, it is just power and does not matter?
If "hospital grade" power cords, plugs, and power conditioners matter for the quality operation of delicate medical equipment, and matter to heavy computer users, then they must also matter for transparent, revealing audio equipment.
No rocket science explanation required.