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.