[eyko]

I'm nearing 40 and I've seen a bit of both. By far the best teams I've worked in had a healthy mixture of experienced developers and younger ones, although I'd say the main catalyst was a mentoring mentality where everyone, young and old, was encouraged to share their experiences (especially the bad ones) in an attempt to brainstorm/crowdsource an improvement to the status quo.

I've also seen the opposite of what you'd expect: a young startup with a very young team that functioned on outdated practices and tools. My first contact with their codebase was a shock to the system – a mishmash of competing coding styles and conventions, barely any of them a best practice, much of it not very idiomatic, an alarming lack of consistency. The choice of tools, libraries and frameworks was (by startup standards) definitely not best in class, and where good choices had been made, the joy was short lived by realisation that they were on old versions, or not using their tooling properly.

But, anecdotes aside, there's a point that generally gets overlooked. Best practices and good developer experience are the result of intentional choices, often in retrospect. The only way to come up with best practices or to improve DX is through experience -- especially poor experiences. I mean, who would've thought that experience was an asset.