What is the purpose of a safety wire through a turnbuckle used to tension guy lines?

Turnbuckles are threaded hardware devices used to precisely adjust and maintain the tension on tower guy wires. Over time, wind-induced vibrations traveling down the guy wires can cause the threaded ends of the turnbuckle to gradually unscrew, which can result in a catastrophic tower collapse. To prevent this, a safety wire is routed through the body of the turnbuckle and wrapped around the ends of the guy wires. This physical barrier locks the turnbuckle in place so it cannot rotate and loosen. It is not designed to bear the structural load if the turnbuckle breaks, nor does it serve as a lightning ground path.