MO is a fun format. I've been meaning to get into it, it's not minidisc exactly, but it is conceptually kind of like minidisc. It's just a regular removable cartridge, and it happens to use "magneto-optical" recording. You can use them for basically anything and other than potentially drivers, there's no special software you need to use to access or write to them, unlike tapes where you'd need to use something like tar, cpio, or a purpose-designed archival or backup tool.
It's
much better in every way than zip, save perhaps for overall availability in the US specifically (where, commercially, Zip "won" because it was cheap and good enough). If you don't need to acquire a very large number of cartridges, then that cost issue shouldn't matter too much, but it depends on how you want to have things set up, etc.
Not only did it have disks the same capacity as Zip, it also doubled as a regular floppy drive (and could even increase the capacity of regular floppy disks to 40 MBs.)
Superdisks found their niche among iMac owners. If you didn't already have a bunch of Zip media, and you just got an iMac, there's a good chance you bought a superdisk/LS-120 disk drive because it cost as much as USB floppy drives did in the beginning, and had the advantage of also working with the LS-120 media.
I'd have to go look around, but my understanding LS-120 media cost around what Zip media did at the time, so it would have been a viable alternative depending on your particular needs.
LS-120 had success in that particular niche. There were a few PC OEMs that shipped them pre-installed, but fewer than were already shipping Zip 100 - in part because Zip 100 predates LS-120 by like three years. (1994 vs 1997)
MO was extremely popular in specific markets (medical and archival types of roles, in particular) as well as in, say, Japan.
Just because something wasn't the most
popular product, either worldwide or in a specific market, doesn't mean it was a complete flop.
Techmoan has a really good video that mentions this kind of issue, but with Minidisc in the US vs. England. (I think it is
this one.) What's said in that video also applies to a lot of different technologies.