Sounds to me like he is asking people to do some basic research first before asking questions, and to supply as much details as possible. This is perfectly reasonable.
I may have got a different impression than you did, but I didn't see this as arrogant. Maybe exasperated, but bear in mind that ESR and other hackers don't get paid for answering questions - they're entitled to be pissed off when seekers are lazy (and waste their time as a result).
Yes - he is preaching to the choir but this is still a good link to point newbies at. Especially ones who don't grok the culture.
"The future will be better tomorrow." ... from the collected wisdom of George W Bush.