I don't know if ATA has caught up yet, but SCSI has always been able to do multiple reads and writes to the drive... which is good if you're doing a lot of reading and writing to the drive.
Also, for a long time studios that did digital recording preferred using SCSI drives because there was less of a chance that there would be digital skipping on those drives.
Perhaps ATA caught up? All I've seen is that those drives get bigger and faster... but I haven't heard anything about multiple writes.