This means you can't pass the game around to your friends or sell it afterwards, which completely ruins the purpose of physical media imo. I mostly play PC these days so this doesn't affect me, but it's a disappointing direction for console games. At least they could've used an empty disc that has proof of ownership.
EDIT: Bethesda has confirmed that only the PC version won't include a disc. Physical versions of Xbox will include a disc. Whew.
That's how PC software/games work. Starfield isn't shipping a disk for Xbox either. Console gamers are enamored with swapping disks that are functionally just DRM keys (due to updates and DLC) around instead of picking their software from an installed titles list. Or they want to sell the game after playing it, which you can't do with software that's sold as a license key.