Touch your radio antenna to your motor or muffler while the plane is switched on. wive's tale?
Metal is heavy. Metal rusts. Metal won't give under pressure. (Say you over G on a downline and get some flutter. A nylon or CA hinge will give a bit and hopefully not rip out of the wood. If it's a large plane and you want more CS "control surface" support use some DuBro point hinges.