Because my use case for headphones very frequently coincides with the times the phone is charging - I cannot both charge and use the headphones at the same time with an adapter, unless there is some weird USB-C monstrosity that would enable this(without just implementing an internal sound card connected over USB).
Gotcha. Personally I never use wired headphones while charging after reading about a woman who electrocuted herself doing that a few years ago (due to a fake power supply).