What is the appeal of a slide device like the Anbernic RG Slide?

I've never used a slide device before and never thought I'd see one until the new Anbernic RG Slide was announced, and while I am intrigued, I don't think I understand the use case for it.

I know that once upon a time, there used to be slide devices like slide phones for back before we had modern smartphones and people had to text alot, and my understanding is that back then, you wanted a slider phone to hide a keyboard so that it doesn't take up all the space on a phone. So I do understand why that might have been popular back before we had modern technology.

However, the RG slide seems to be using the sliding mechanism to hide away twin sticks and the standard set of handheld d pad and buttons. Why do we want this necessarily? I mean when the device is off, I don't think I'd care if I pressed a button accidentally, and the part I usually am concerned with protecting is the screen, so if anything, I'd want a clamshell device instead.

So why then, a slide? Is a pure nostalgia thing, for those who remember the days of yore when these types of devices existed? Or is there another practical reason?