This is just a computational Perspective.

Gottesman-Knill Theorem:

"The theorem proves that, for all quantum algorithms with a speed up that relies on entanglement which can be achieved with a CNOT and a Hadamard gate to produce entangled states, this kind of entanglement alone does not give any computing advantage."

Entanglement alone is not sufficient for algorithmic speedup.

Again Wikipedia:

"The reason for the speed up of quantum computers is not yet fully understood"