I'm not disagreeing there's an issue, I'm just not sure that it's deliberate. People refer who they know socially or have worked with in the past - your friends

I'm not disagreeing there's an issue, I'm just not sure that it's deliberate. People refer who they know socially or have worked with in the past - your friends will tell you they're looking for a new job, but your current co-workers mostly won't. And most people tend to stay within their own cultural bubbles when it comes to making friends, both because it's easy, and because making friends with anyone as an adult is hard. I too, am very happy to refer anyone talented regardless of background, and I think most people are.