James, that's a good argument, but if that's the argument that you want to make then please show data back to 2007, not to 2009. Also, I stand by my statement that there is a negative correlation between active editors and mobile pageviews in the data that you showed. Correlation and causation are different.

If you watch Jonathan Morgan's presentation, you'll see that he says that his favorite theory about the decline in active editors after 2007 is the rise of the popularity of Facebook. I think everyone would agree that there are other issues at play as well. I believe that Jonathan says that new editors were welcomed more readily in Wikipedia's older days, and now they are more likely to receive template warnings on their talk pages.

Other possible factors include

* The length of the review time at Articles for Creation, at least on English Wikipedia, which means that contributors may lose patience before their drafts receive reviews

* The trend of preferred Internet devices switching from desktop to mobile, combined with the difficulty of contributing text from mobile, as some of us have mentioned in this discussion

* Shorter human attention spans (is there any data about this?)

* Preferred modes of social expression switching from lengthy blog prose to short strings

* The number and complexity of policies and laws that govern Wikimedia content

* Increased surveillance, censorship, and criminalization of Internet activity, which may deter potential contributors

* The reputation in social media and technical communities that Wikipedia is a hostile environment; I have heard this personally from other tech open source enthusiasts

Other people on this list may be able to contribute additional ideas.

I agree with Stuart that Wikipedia may be part of an Internet-wide trend of trolling becoming more common, and that making communication and editing easier on Wikipedia is likely to make trolling and vandalizing easier. My bigger concern is that lots of resources are being poured into VE and Flow but that VE and Flow address problems that are of less significance than others that we've mentioned in this thread, particularly the difficulty of mobile editing and the increase in hostility. AfC and the Draft namespace would be other good territories for investigation of their impact on editor retention and content creation.

I hope that VE and Flow will be net positives (I am generally supportive of the VE concept, and cautious about Flow) but I feel that Wikipedia's biggest problems may lie elsewhere, and I would like to see resources that are proportional to those spent on VE and Flow get spent on some of the other areas like AfC and the on-wiki culture. These would need to be addressed in collaboration with the content communities, and the WMF Strategic Plan update would be a good time to elevate Wikimedia's cultural issues as a priority, with a continuing emphasis on mobile and new modes of consumption and creation.

Pine