Integration into file formats.

This is the kind of thing that sounds seductively attractive and then you actually try to do it and the metadata needed to keep track of everything blows up exponentially (literally, not in the modern meaning of "a lot"). And fragmentation increases massively, which turns out to matter even on NVMe drives.

There's specialist cases where this makes sense, but it's no free meal. Or maybe it is a free meal, in the sense that the drinks now cost 50% more.