I know of more than a few "Old Sages" in several different disciplines that no longer post on their respective forums, to which they once took pleasure in contributing (but they still lurk frequently), because of the slamming they'd get (usually disrespectful, and from self-proclaimed "guru's" themselves) over the years. They just figured "Why bother." Can't say with any degree of certainty if that's what's happened in this case.
Dean is top-notch, alright. He once took the time, via email, to school me on a few of the finer points of his bow design that I had trouble grasping. I DO recall that it was done off-forum because of the the shouting down from some folks about how what he was saying made no sense. But it did, naturally, make perfect sense and I'm grateful for not only what he said but the gracious and matter-of-fact way he said it. Not only a man of deep and broad knowledge but also possessing an innate ability to share it in easy to understand ways: Darn rare, indeed.
Just my two cents. But civility is too often lacking on most forums by virtue of their being so limited with regard to personal interaction. This site is by far kinder and more welcoming than most, or maybe any others that I've been to. But it still happens. That's just human. So, who knows...