Originally the RAR file format was created to make it easy to put a large amount of data onto floppy disks, before writable CDs were widely available. The indiv

Originally the RAR file format was created to make it easy to put a large amount of data onto floppy disks, before writable CDs were widely available. The individual .r## files were sized to completely fill the disk space, so you didn't have to worry about organizing the files to minimize the number of disks needed. After CD-RW drives became common RAR files were mostly used for uploading and downloading as you describe, to avoid file size caps and to make it somewhat easier to fix corrupted chunks. By the time the data being shared was filling the CDs we had writable DVDs, so RAR wasn't needed to span CDs. Then writable BluRay came around before DVD spanning became necessary.