I don't mind my washing being darked on but I did mind it being rained on.
Taking a comfy seat on the therapist's sofa...
I think it stems from my childhood. My parents separated and my Dad made sure be was very fussy about having his house clean because he didn't want to be a bachelor with a house that wasn't clean. Fast forward thirty years and he has developed a fabulously entertaining obsession, staying with him is better than a hotel. Laundry would not be left on the line overnight, not for fear of being darked on, but because it is somehow not the done thing. Ironing my lacy underwear and DHs socks apparently should be the done thing. He also bleaches the house after I've visited for a while, I try not to take it personally! If it rains, someone is supposed to "get that washing in", urgently, drop everything, including toddlers, to rescue the laundry from the rain. It gets wet, he is as dismayed as when his football team loses. It then needs washed again because even though he lives somewhere with super clean water that is bottled and sold, rain is not clean. Also things get more wet, so have to wash them again.
I've spent so many years trying to avoid turning into my mother. As a result, I unknowingly turned into my father!
So of course laundry that gets wet in the rain needs to be washed again. It got wet in the rain and it has rain all over it!
It is living on the wild side to have laundry darked on. I would do it only for the thrill of living dangerously.