Currently this is how it works. We were thinking about “inifinite propfind” but didn’t proceed with it for now to save the server from overload. Our priority is to have reliable sync, have sync as a virtual file system to save disk space as quite some customers have even larger amounts of data in the meantime.
We are also experimenting with a new set of APIs “CS3 APIs” for ownCloud Infinite Scale. Please start here if you are interested: What is nexus? And where did it come from?