This is one of those "I don't need it until I need it and then I REALLY need it" addons. If you're working with massive scene files containing tens of thousands of objects (e.g. large architectural developments), being able to offload areas to separate files is crucial. But when you need to edit those areas quickly, this addon becomes so helpful. Thank you to those who develop and maintain it!
Easily one of the most helpful addons I've seen in the last few years. It's exceptionally well done.