Because you can package and deploy OS components with it. As a result you can build an OS with it, do foolproof updates of it and …gulp, happy tear… rollbackcomponents without involving any other system like a special filesystem.
My bravery comes from being a software guy that’s been doing OS software development for over a decade so I believe my opinion is somewhat informed. 😂 I’m currently working on a software updates implementation for an automotive OS.