Because what everyone wants is more invisible closed-source software running on underpowered CPUs? Not to mention the limitations on performance, capacity, and

Because what everyone wants is more invisible closed-source software running on underpowered CPUs? Not to mention the limitations on performance, capacity, and reliability scaling that would be inherent in binding the database instance to a single disk device. Or were you suggesting that each of these tiny controllers running deeply proprietary software should also form a distributed database in concert with host software or HBA controller firmware? To say that this is not a good idea would be putting it mildly. The existing efforts to build more functionality into disk drives, starting with FDE and now with some object-store-like interfaces, sounds real appealing at first. Less software to write, functionality everywhere, disks seem to Just Work today so wouldn't it be nice if they could Just Work in some more ways too. However, as soon as you start thinking about building something larger or more interesting than a toy, it becomes apparent that the disk drive is the wrong place for this. The knowledge of the problem is not present at that level of the system, and the interfaces and processing power are inadequate to express it. The problems of error recovery, scaling, and debuggability cannot be solved there. It might be useful for a few of the very smallest consumer-grade applications where none of these concerns are significant (nor likely to be solved by a higher-level vendor anyway), but it's not generally viable.