It's worse than that. Most people who stream would have their headphones plugged into their streaming computer and they can hear the game audio being echoed back to them via OBS or whatever. So even if Sony were designing for streamers they wouldn't "implement dual ahdeo" because the number of people who would do that is basically one - Phil. Maybe if he literally ever invested money in his big boy business professional gamer setup he would know that, but instead he will keep using his AverMedia Shitbox 5000 until it dies and he goes offline for a month while he begs for the money to buy a new one (and then keeps blowing it on Champions). As with all other things, the "dual audio" thing is a microcosm of Phil's laziness, narcissism, and need to externalize blame.