It's seriously hilarious to me that something like Linux will literally let you uninstall the bootloader and reboot without installing a new one and won't say shit about it. :D
It's by design. What if I boot from USB? Then what's on the disk is irrelevant. I can boot a kernel off a USB drive and chroot into any drive i feel like. Hell, I could boot from a USB and then chroot into my broken drive and reinstall the bootloader without having to reinstall the OS.
Lets see MS pull that off. I bet once you corrupt the registry enough you have no choice but to reformat and start over.