It relies on pure, unproven postulates, which somehow work, to further Quantum Mechanics without ever questioning the need to delve deeper.
They can neither prove why the wave function represents probability density, and neither the Born rule about probabilities being the square of the amplitude, without creating assumptions, and even when they do, they depend on pre assumed arguments and attempt to justify their already accepted ideas by showing that they work and make sense. Heck, they cannot even reason the Schrödinger Equation, or other generalizations like NLSE, Dirac's, etc.
No one has yet come up with a mathematically rigorous derivation of these postulates without either assuming them, or the H-space, or involving circular arguments.
Most hilariously, they accepted the absurd reality of wave functions breaking down upon measurement. When you ask "why" they shrug !
Today we employ Decoherence to mask these problems, and even that just slightly eliminates the dynamics of wave function collapse, arguments remain circular. Do you have any argument for the Born Rule, Schrodinger Equation, and the Copenhagen interpretation except that it works and 'makes sense' if you assume H-space [again, an assumption!] ? And simultaneously, you blindly accept entanglement as well !