Do writers get better as they grow older?

I had the same thought as the (forthcoming) NYT book review essay re the New Yorker 20 under 40 fiction issue: Can you really call a writer in his or her 30s an "emerging" writer or a "budding" talent? They ought to be in full bloom by their 30s, I think. And Tannenbaum in the NYT cites many examples to show that most of the great writers did their best works at the relatively early age of 30+. There are a few exceptions - he does skim over these - including a few who matured with years - Roth and Updike recently, James and Mann more distantly - but they're the exception. And the reason seems obvious: your craft, your way with words, is not going to improve much after 30+. Since most writers draw heavily on childhood and early-life experiences for their first works, the determinant is can they continue to draw on this experience with ever greater insight (Updike did), or will they mature and write about great issues (as did Mann) or mature adults (James, Wallace Stegner, Roth to an extend, Bellow). That's to say it's easy to pick 20 under 40, especially if you've already published most of them. I have a 20 under 30 anthology from some years back - much more of a challenge, and few of its entrants are known today. Why not bracket all writers, as in a road race - give awards for writers in their 60s, 70s, 80s, say (and not based on lifetime personal best but on current production). As friend Peter Phipps first said to me about running: You don't have to get faster, just older. It would be nice if older writers got better. Sadly, few do.