OS tribalism aside, I do agree that something like this happening obviously isn't appropriate for a serious daily driver. Of course we'll never know specifically what happened or how to fix it, but I have a hunch something happened with the bootloader which would've been very easy to generate a new configuration for or even reinstall specifically instead of reinstalling everything and hoping the same problem won't happen again.
When I was first learning Linux for some reason I outright deleted the entire GRUB partition but thanks to online spoonfeeding I found out how to get it back up again like nothing had ever happened.