I mean that they didn't survive as a technology or increase on density much after their peak. I think Jaz drive were the highest density, although I admit that I haven't looked into it closely.
I used both Zip and Jaz drives in their day, so I am definitely familiar with them. Maybe it's just the drive failures and reliability that have left me bitter with Iomega. For example, I have had Jaz disks actually explode inside the drive, taking all of the data with them.
I don't consider Zip disks to be a contender for the Sony micro diskette format, but rather its own format. The magneto-optical drive, as seen in the NeXTcube, is the future I would have like to have seen. 230MB floptical? Yes, please!