Frozen Pipe in the Attic...Not Good!
This damage is from a frozen pipe which burst in the attic and was not discovered right away.
Water weight brought down pieces of the drywall and insulation right into the room. Then the water ran to several other areas.
In these situations, with water not only affecting the ceilings, it also affects the side walls with water coming from the top down.
As the water affects the full length of the wall, it is often necessary to remove all or parts of the wall. Lower walls and ceilings can often be dried effectively. Upper wall can be a booger to dry.
This particular home had paneling over drywall, which complicated the drying as the paneling tends to block the drywall drying.
The paneling made a cool rustic look though.