Those magic black boxes need to be implemented too. Relying on the strategy "someone built them in the before times so we don't need to worry" has severe failure modes.
As if the techniques in SICP was the only way to build those black boxes?
Do you honestly think someone who just learns python really well without touching SICP can't build a library?
They can. It's just they can't build the library in the idealized lego like modular way that SICP is promoting. This style is definitively better, but it is in no way required.
