Well I guess it's like fermented foods, technically they're…

Well I guess it's like fermented foods, technically they're rotting and moulding yet there is so much evidence to support beneficial gut bacteria. I myself have used saurkraut and seen dramatic benefits. A friend of mine cured crones eating it.
Natural moulds and fungus is a breakdown, where as what we see as black mould in the home is due to inorganic living, and walls covered in toxic paints and substances, reacting with the outside world.