My statement wasn't precise enough, you are correct that random access API is provided. But it is ultimately connected to the `accessPayload` function in btree.c which comment mentions that:

    ** The content being read or written might appear on the main page
    ** or be scattered out on multiple overflow pages.

In the other words, the API can read from multiple scattered pages unknowingly to the caller. That said I see this can be considered enough for being random accessible, as the underlying file system would use similarly structured indices behind the scene anyway... (But modern file systems do have consecutively allocated pages for performance.)