Can’t imagine adding soy sauce to white rice. My moms as white as you can get without igniting in sunlight, but rice simply wasn’t a thing they ate (potato’s or pasta), unless you wanted to be exotic and go to the Chinese restaurant.
Growing up, it was mostly Arab food. Definitely no soy or equivalent there, but rice was generally served with something soupy anyways.
As an adult I try to avoid white rice, too easy for me to overeat. Only sauce that touches it, is in the food itself. I don’t mind plain rice. I know many love the flavor, but I boring unless you doctor it up. But it’s functional and that what i want from it; a non-offensive pallet to soak up the sauce, fat or juices of the meal.
That being said, that suggestion to add soy or fish sauce directly to the cooking liquid seems like genius. I’ve done similar things with quinoa, but the most I’ve ever done for rice is a touch of butter or chicken base. Going to have to try this for rice.