I agree with some of that SDQDI particularly your 2nd & 3rd paras. I've met Dafydd and he has a formidable intellect and the credentials to back up his opinions. I suspect that his years of battling the "0.5 wits" in CASA and it's predecessors have caused him to not suffer fools gladly, and some here didn't take kindly to that. You're also correct, it is Ian's site, but isn't a site like this devalued when the people who know quite a lot give up and leave, and the people who know it all stay?
Happily there are still quite a few here (and in the naughty corner) who don't know everything and who's contributions are much valued and appreciated. But it could be so much better.