More experienced developers are also more willing and able to take on a pre-existing production code base and clean it up and plan how to divide and conquer to

More experienced developers are also more willing and able to take on a pre-existing production code base and clean it up and plan how to divide and conquer to improve, migrate and replace it, while younger developers often prefer to work on greenfield projects or want to throw out and replace existing work. Younger management doesn't always understand this difference, and more experienced developers might be contributing in avoiding a lot of costly mistakes but this benefit is mostly invisible. This is really down to what side of the tech industry it's happening on and what that side needs. Working with new web and mobile technologies delivering novel applications for consumers are more suited to younger people as opposed to say developing, maintaining and evolving systems for aviation, transport and military automation and safety or certain parts of finance.