I disagree, though I know relatively well how much people contribute. I'd rather blame the mailing lists if simple enthusiasts caused too much noise. What bores me more than non-contributors running their mouths is people choking during a marathon.The single largest factor in making the atmosphere unpleasant is people who aren't contributing to Debian running their mouths on our development lists.
http://lists.debian.org/debian-devel/2008/12/msg00229.html