It's like the joke of the mathematician giving an exposition of a complex proof. At one point he says "It is obvious that X", pauses, scratches his head, does a few calculations. Leaves room for twenty minutes and returns. Then continues "it is obvious that X" and goes to the next step.

Deep in the field, it's fine for machine learning experts to say "everything just works" [if you've mastered X, Y, Q esoteric fields and tuning methods] since they're welcome to "humble brag" as much as they want. But when this gets in the way of figuring out what really "just works" it's more of a problem.