Oh look a state of the art Audio NLP model. Something that would be very useful while listening to you on your phone to send you ads... something they totally aren't doing
Facebook don't need to listen to you - they have enough other behavioural analytics to predict what you're going to want to buy better than you can yourself.
They have been collecting as much data on people as they can. They've got the tech to listen to you, why wouldn't they use it?