That's literally what they said in their first sentence.

Yes, and no.

They started out right and acknowledged that things can be different in different climates. But then in their second paragraph they made a categorical statement: “Still, drying clothes indoors has no ill effects, I have no idea where you got this.”

That is a general statement. They don’t think drying clothes indoors can have any ill effects. Ever. At any humidity level.

So they realise that the drying time can change quantitatively. What they miss is that there are qualitative effects which can happen too. And in their hurry they dismiss other people’s lived experience.

You're right, I do understand that if it takes days to dry, the dampness has a good chance of allowing mold to form, and that can be extremely harmful.