Everyone has heard my feelings on the NTSB to their exhaustion.
However, in fairness, once you understand the NTSB is a political entity, it makes their actions much more logical.
At some point there has be a good enough regulatory or fact finding backstop. Both they and the FAA are that. Not outstanding, and both are quite demonstrably susceptible to regulatory capture despite their protestations to the contrary. Oddly enough, that capture seems much more prevalent at the higher levels than the working levels.
That said, the NTSB will happily present a "good enough" finding in the absence of the clear cut cause, and if it can have a crew nexus even better. One only has to look at the considerable time and effort that ALPA alone puts into independent accident investigation capability as a silent referendum on full faith in the NTSB. Politically, the NTSB wants to create public faith in the air transport system, not necessarily create an objectively safer system.