Why did the Quantum Mechanical Model replace the Bohr atomic model?

The Bohr model has descriptive power (it describes what we see) and predictive power (it correctly predicts new results). It shows that there are 2 electrons in the innermost shell, then 8, 18, and so on, but it doesn't explain why that is the case.

A scientific theory should, however, ideally also have explanatory power—that is, it should explain why the things it describes and predicts actually happen.

The Pauli exclusion principle in quantum theory explains why there can only be a maximum of two electrons in each orbital, and that they must have opposite spins.

It demonstrates that an s-orbital, totaling two electrons, is present only in the inner shell.

An s-orbital (2 electrons) and three p-orbitals (3x2=6 electrons) for a total of 8 electrons are present in the second shell.

There are a total of 18 electrons in the third shell, consisting of an s-orbital, three p-orbitals, and five d-orbitals, each with two electrons.

Seven f-orbitals are added to the fourth shell.

The explanatory power of the quantum theory surpasses that of Bohr's theory for this reason.

The Quantum Mechanical Model replaced the Bohr atomic model because it better explained the behavior of electrons and provided a more accurate description of their positions and energies in atoms.