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've had some cars where simply changing the head gasket was a complete solution, on other cars there has been cylinder head damage which required skimming. On one, I had a melted piston and two bores full of water. The only way to find out is to take the head(s) off.
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.