Well, I would say that the reason is not the sound per se, it's the inability to turn off the sound. This software solves that.
This software doesn't deactivate the sound of the keyboard. I feel like I am taking crazy pills today.
Obviously it doesn't change anything in the physical world. I think you're just misunderstanding the implication. If this software fulfills the need, individuals would not need to use keyboards that physically create the sound. Whether that would actually happen is a different matter.