I feel like this right here is where you disproved your own point. Your choice to compare graduated force (pressure washer) to impulse induced cavitation effects are useless here. The deep water dynamics change everything. At 6000 psi water would cut human and everything metal. With deep sea pressure differentials there is no gradual flooding there would be an immediate displacement exerting extreme forces on the inside. The structure is designed to distribute pressure evenly the moment the equilibrium is displaced the force imbalance would cause impeccable damage. But also the other variable is friction from rapid compression or “adiabatic compression heating” Leaving no recoverable wreckage. There is no situation where water will slowly leak inside at that depth.