If you don't need to push technology to its limits, you don't need to understand the stack. Everything basically works, every program will work on both SSD and rotational disks, it will just have different performance characteristics.
Some of the purely software opaque abstractions are bad in the sense that all abstractions are inherently limited, and sometimes your job is easier if you can just access the layer beneath and get your job done. So a transparent framework is one that "doesn't get in your way" (like AWT for Windows GUI development versus MFC differ a lot in giving you options to customize what you do using raw win32 API).
Some of the purely software opaque abstractions are bad in the sense that all abstractions are inherently limited, and sometimes your job is easier if you can just access the layer beneath and get your job done. So a transparent framework is one that "doesn't get in your way" (like AWT for Windows GUI development versus MFC differ a lot in giving you options to customize what you do using raw win32 API).