How do we learn? We learn most everything by interacting with others. When my mom stubbed her finger and clutched it and yelled “ow!” and said “that hurts! … mmm … painful … ow …”, her face and body instinctively contorted in response to a sudden sharp pain. My young mind instinctively mapped those involuntary changes to her face and body onto the little map we all have within our brains of our own bodies. When my face and body contort like that, it is because I feel the same thing she is feeling, what I thus learned to call “pain”. We instinctively learn via empathy: by assuming others are essentially like we are and that share the same essential reality. That is how we learn from others and their works, and since our general sense of reality comes from these interactions, that is how we learn most everything.
Philosophical zombies are silly parlor tricks: if you honestly countenanced the possibility that others were not essentially the same as you, you’d have no idea what to think about your own thoughts (which are built atop a structure created by assuming others are essentially like you), and so philosophizing would cease to be meaningful. Also, you can’t stand such a Reality, and so philosophizing would cease to have a point.
When doing math, you can work on purely speculative topics. What’s the harm? And sometimes they turn out to have an application. But with philosophy, there’s no point unless the ideas are livable. Indeed, much harm has been caused by people pretending they could travel with ideas to conclusions that actually make no sense to human hearts, minds, and bodies.