Bios flashing only fails when people are lazy or stupid with it, like using windows based apps to update major bios updates, every board manufacturer has some sort of feature built into the bios to help you safely update it, gigabyte have Q flash, asus have ez flash, msi have M flash, ive had 4 am4 motherboards from different manufacturers and never bricked one.
As for boards that come with bios flashback, the only one msi have is the x370 titanium, but it's a very expensive board, gigabyte have dual bios, not sure with asus or ASRock, you'd have to check out the features section on the Asus website under x370 boards.