The physical act of wearing the pendant is not the issue, it's the reason for wearing it. The same reason when you go to a Trivium concert and everyone is wearing black sleeveless vest tops, because the main vocalist does! 99% of these people wouldn't even be wearing these pendants or even know what they were unless they saw the band wearing them....fact.
Not sure what the comparison with metal music is all about, looks like waffle to me.