If someone observes measurable benefits after (e.g.) breathing through one nostril for a while, I'd consider it important to know exactly why. Maybe there are important things about the mechanics of respiration that we haven't understood yet. Dismissing such phenomena with "If it feels good, who cares why?" seems counterproductive in the long run.

OTOH, if no one sees measurable benefits, then the various anecdotes from practitioners really are just bias in action, and (IMO) are not worth expending further thought on.