Ask HN: Dual-boot using BIOS to switch instead of bootloader?

Whenever I set up a dual-booting machine, the bootloader feels magical and precarious. Sometimes Windows just decides to overwrite it, I wouldn't know how to repair GRUB or remove it and install it fresh myself without risking breaking everything, etc.

But if I've got the two systems on separate drives, couldn't I just let them each pretend they're the only thing installed - each with its own bootloader - and configure my BIOS to always prompt me for which boot media to use? That seems much simpler and safer. Is this something people do? Are there any downsides to doing it this way?