Why? Controller support is baked into Engine OS. If you didn’t know, Engine OS is a common codebase for all of the Prime devices.
The actual DJ Software integration needs to be done by the software makers, in the SC5000/SC6000 series it’s a little different because the software makers need to use the SDK provided by Denon, however, because the SC5000 shares the same codebase and is Serato compatible, we can extrapolate that this is not on Denon.
Your annoyance is placed on the wrong company here, I would suggest making your voice heard in the Serato forums, my understanding of this is that Denon has done what they needed to do to enable support for the DJ softwares, the rest is on the developers of said DJ software.
Yeah that’s not how this works… Denon, and Pioneer in this case release the products and provide the SDK/mapping materials to other vendors for them to add support.
It’s different for controllers that are built around Serato as the hardware is built in parallel with software support, otherwise there would be no point in releasing it. However, the prime series, as well as Rekordbox controllers & Pioneer standalone devices, are not dependent on Serato so don’t develop the hardware in parallel with software support.