Does a blown head gasket most likely always mean there is engine damage? In your experience have the majority of cars you've seen with blown head gaskets also had engine damage?
I have changed head gaskets on older cars (generally with cast iron heads) that have had no other damage, likely as a result of not enough clamping force on the head gasket and over time it fails. On more modern vehicles with better bolt spacing design, there is normally a fault which triggers the head gasket to fail, such as a warped or corroded head.
Once the gasket has blown, owners can also cause further engine damage by running the engine low on coolant and overheating the engine. On a large truck engine I rebuilt once, one of the bores was cracked due to hydraulic lock on starting due to a leaking head gasket.