Noone is disputing the advantage of RAW. I tried to provide the view from a pure development perspective, looking at a feature backlog.

It "just happens" to be selectable because it is a byproduct of the internal development: The existing RAW format is used internally during development and tuning of the product, and is implemented to work with vendor-internal processes and tools.

Supporting DNG would require a SEPARATE development, and it would still not replace a proprietary RAW-format in the internal toolchain.

(because the DNG patent-license comes with rights for Adobe as well as an option to revoke the license)