I am thinking more along the lines of the loss of quality of
previously high quality
articles, which are already incredibly small in proportion, such as
"featured articles."
Traditional content production methods asymptote in quality, but the
editing process in
place at Wikipedia (which is only one possible wiki process, and also
one of the most
successful, but does not necessarily speak about wikis in general)
encourages articles to
gradually increase in quality, and then again decrease. It is unknown
if they will
stabilize (which brings about thoughts of a 1.0) There are plenty of examples of this phenomenon: http://en.wikipedia.org/wiki/Wikipedia:Former_featured_articles
I'm sure there are plenty of examples of that too.
Does that mean that Wikipedia as a whole is low quality? No.
The demoted articles could still be very high quality, and comparable to equivalent entries in Brittanica.
The demoted articles could be a very small portion of the featured articles.
This could be due to changing featured article criteria, but in
general, the claim that
simply starting a wiki encourages high quality content is lacking
evidence. If anything,
wikis encourage the addition of noise to high quality content. Adding
noise to turing
complete wiki syntax can quickly snowball, turning into an aggregation
of media that lacks
coherence.
The fact that wiki technology and social process were able to reproduce Brittanica in 3 years is good enough evidence for me. And it's an evidence that has been measured objectively by the Nature study.
In fact, I would say that by now, the burden of the proof is on those who claim that Wikipedia is poor quality and that the wiki process and technology is not working. To date, I haven't seen any solid objective empirical evidence to that effect.
But I am opened to persuasion.
Alain
BTW: I agree with Andrea that wiki does not AUTOMATICALLY lead to quality content and active communities. Creating a community that works is still a bit of a black art. The point is that it CAN work, which came as a surprise to most people, including myself.