I doesn't make as much sense since there is a silver 10 year badge that indicates a forum join date of 10+ years. I'm assuming the original gold one was kept around to differentiate the "original year" members. A relatively simple update would be to replace the gold badge with something that indicates our OG status.
Not a big deal of course, but every time I look at both badges I have this same thought.
Gold banner is linked to those people that joined before the first 10 year banner give away. The response was such that the silver banner was introduced for people after that initial batch.