There are two main things it's good for.
1. It has a preamp for your microphone. So even in bypass it supplies line out.
2. You could use it as a harmony box. For example take a vocal track you have already recorded and run it into the line in and then record the output back into the sound card on two more tracks. This might result in a tiny bit of delay but you can use the process/slide function to fix that. Just trim some from the front of the clip if you started recording at zero so you will have room to move left.
Not just vocal ! you could even do this with a guitar track for that southern rock double lead sound. Like re-amping but with a live level box.