Hunting ulua with no tagline or reel is just plain lolo
The few people that I've seen use belt reels in real life have kept it only as a spare. The reel was attatched to their belt and used only in emergency situations - i.e. their gun reel jammed & they needed to get to the surface. The belt reel line could be clipped to the gun & used to make sure your gun didn't disappear.
While I don't like the idea of something hanging off my belt to snag kelp, rocks, etc. - I can see its value if you are trying to shoot pelagics with no float/floatline.