The other commenter is also right, but CD-RW also had two fatal flaws:

1. It was notoriously unreliable. Data would fail to write and corrupt the disk. Disks would often fail after a few uses.

2. It was horribly slow, both to read and write (in my experience). In many cases it was faster to burn a CD-R with lots of files instead of moving individual files to a CD-RW.

Maybe it was just my computer at the time, but CD-RW was more of a novelty than anything. It could have been good, but it simply just didn't do what it said on the tin.