Regardless, you see how a $9 adapter, even purchased and replaced multiple times doesn't even come close to your supposition that Apple expects you to get rid of your $500 headphones? Only when the cost of replacing those $9 adapters, or the inconvenience of relying on them makes the trade off unacceptable for continued use of your headphones, does that factor into the equation.
Personally speaking, I have a Lightning adapter on the end of my headphones. It basically lives there and never gets used with anything else -- I've never lost it, or left it behind. For $9, I have purchased additional adapters for the cord in my car and the cord in my house. That $18 spent is far better trade-off in my opinion than getting rid of a $500 pair of headphones.