Many audio editors have limitations in loops, not only Wavelab. It is the old Audition which was the most versatile audio editor ever. Unfortunately, the more it departed from the original CoolEdit, the less useful it is for special jobs. Unfortunately, yes, I am a cornercase with my research.
The multiple loops can be used in some samplers to make the sound less repeating when played back. If only single loop is played over and over, it becomes repetitive soon for the human ear. The loops have to be overlapping, so that the software can randomly travel through them when played back. One such software is GrandOrgue (also on SourceForge).