I mean, they literally show the use case for it on some of their the videos. It's not a general purpose one by any means, but this one is an actual Pro box, not a "I'm a consumer and just want the name Pro on my device" box.
The current use case is music production. Logic Pro. I have an Akai MPC Gen 2, with a touch screen for moving around the DAW and manipulating the virtual instruments. Logic Pro with the same level of interactivity would be fantastic, and no the iPad version doesn't cut it. I'm actually very interested in it for this specific reason.
Price? Well, I paid around £4k for my Intel 4Tb beast in 2019 to store all the sample-based instrument libraries I have. It's not a "let's buy this to look cool at the coffee shop" machine, although I'm sure some people will. I'm actually very interested in it for a serious step up in the way music production works.