This is news to me.
Because a strung neck is under constant tension. Without some sort of reinforcement (doesn't necessarily have to be a truss rod, I admit) the neck will bend over time. Just because something is a tradition does not mean there isn't a better way to do it. The fact that many of those old guitars have to be planed and refretted is a testament to this.
I never thought the weight of a truss rod would be an issue unless it was made out of rebar.Alan Carruth wrote: ↑Sun Oct 28, 2018 8:01 pmThe big advantage of an adjustable rod is the adjustment. The big disadvantage is the added weight. One of my former students made himself a titanium rod that was really light, but I don't know of on on the market. Too bad. Maybe I'll talk to the guy I get my rods from. They would be expensive...