> Is structural editing a genuine advantage over line-based editing?
A full-featured editor should support both. Line editing is convenient for some editing operations/workflows where you don't necessarily have a well-formed AST at all times. But for many other workflows, structural editing is preferable.
A full-featured editor should support both. Line editing is convenient for some editing operations/workflows where you don't necessarily have a well-formed AST at all times. But for many other workflows, structural editing is preferable.