A very smart developer who I respect once said something like: when you are young, you have lots of energy and want to learn/use the latest technology. As you get older and gain more experience, you start to see the patterns. It's not about the technology, there are repeated themes and solutions. But when you start realizing this and have accumulated 7 years of experience, you may be transitioning out and wanting to begin starting a family. So the people who might be most qualified might be wanting to leave the intensity of coding for the relative stability of management.

So perhaps n years of experience is a cludgy filter for the relative graybeards who understand that technology is just a tool, not an end in itself.