Japanese games primarily designed for use with NEC PC-88 and PC-98 computers that came on floppy disks had an even worse problem:

In order to save your game, you have to write to the floppy disk, usually wash disk needed to write somesort of data. Unfortunately, this means that the disk cannot be read-only protected. You probably see where this is going, but this sadly led to some players having uncompletable copies of games because they wrote to the wrong disk and accidentally ended up overwriting game data with save data.

Some games came with manuals that warned of this, and some games spent the cost of disk space to store actual in-game warning screens to try to prevent this.

EDIT: It has come to my attention that most people reading this probably don’t know this because they are too young, but these games that came on more than one floppy disk usually required you to insert at least 2 disks at the same time, one into both of the available drive slots. Then you would swap one or both out, depending on where in the game you were and if you needed to save or not. Each drive only appeared as a letter to save (usually A: and B:, which is why computer harddrives often start at C:, fun fact), and sometimes it didn’t prompt you to make sure after you selected one of the drive letters from the ingame menu that showed you nothing but the letter of the drive. So if you selected the wrong one, that sucks for you because they sometimes didn’t bother to check if there was already data on that disk or not before writing, which could cause data corruption, usually towards the end of the game.