My understanding is that’s true of basically all insulation. Old structures were built with the assumption that they’d breath, and insulation wasn’t as important since they’d be heated by fireplace in the winter (either directly or using the fire to heat water for radiators) and air conditioning wasn’t a thing yet.
IIRC it can also cause the structure to rot if they get the vapor barrier details wrong.
My understanding is that’s true of basically all insulation. Old structures were built with the assumption that they’d breath, and insulation wasn’t as important since they’d be heated by fireplace in the winter (either directly or using the fire to heat water for radiators) and air conditioning wasn’t a thing yet.