Deutsch's algorithm vs classical algorithm

[maxverywell]

How the Deutsch's algorithm outperforms a classical algorithm?
In both algorithms we need two particles (two bits and two qubits). In the quantum case the two qubits are processed by the FCNOT gate simultaneously but it's equivalent to two classical "black boxes". So if we take two classical boxes the two bits are processed simultaneously too and the two algorithms are equivalent in power.

 

[Joseph14]

How the Deutsch's algorithm outperforms a classical algorithm?
In both algorithms we need two particles (two bits and two qubits). In the quantum case the two qubits are processed by the FCNOT gate simultaneously but it's equivalent to two classical "black boxes". So if we take two classical boxes the two bits are processed simultaneously too and the two algorithms are equivalent in power.

Why are you assuming putting a qubit in superposition into one blackbox is equivalent to two classical black boxes?