[jstimpfle]

I think I agree with your "buy-in idea", but adding that the Unix filesystem abstraction is almost as minimal as it gets, at least I'm not aware of a simpler approach in existence. Maybe subtract a couple small details that might have turned out as not optimal or useful. You can also in fact write a string to an offset on an SSD (open e.g. /dev/sda), you only need the necessary privileges (like for a file in a filesystem hierarchy too btw).

A database would not work as mostly unstructured storage for uncoordinated processes. Databases are quite opinionated and require global maintenance and control, while filesystems are less obtrusive, they implement the idea of resource multiplexing using a hierarchy of names/paths. The hierarchy lets unrelated processes mostly coexist peacefully, while also allowing cooperation very easily. It's not perfect, it has some semantically awkward corner cases, but if all you need is multiplexing a set of byte-ranges onto a physical disk, then filesystems are a quite minimal and successful abstraction.

Regarding STL containers, I think they're useful and useable after a little bit of practice. They allow you to get something up and running quickly. But they're not without drawbacks and at some point it can definitely be worthwhile to implement custom versions that are more straightforward, more performant (avoiding allocation for example), have better debug performance, have less line noise in their error messages, and so on. The most important containers in the STL are quite easy to implement custom versions with fewer bells and whistles for. Maybe with the exception of map/red-black tree which is not that easy to implement and sometimes the right thing to use.