There is a bit of truth to the story. If the engine is wore out enough to need new heads then the rest of it is probably on it's way out too.

If you ONLY fix the heads why would it surprise anyone the rest of the worn out engine gives up the ghost not too much later?

Common sense.

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.