WHERE WIKIPEDIA WENT WRONG
The goal of Wikipedia ("Wiki" for short) is admirable...to bring people from all backgrounds together in a collegial and cooperative environment to in order to put their collected knowledge into an online encyclpedia. However, things have gone seriously wrong.
The core causes:
1) The inherent pettiness, greed, and selfishness of mankind. Wiki is a reflection of the real world with the same strengths and weaknesses. The kind and helpful editors are all too often driven off by those with agendas or who are just plain mean.
2) Wiki's anonymity is a two-edged sword. It both protects the innocent and allows the bad users to hide. If a bad editor wants to edit, there is no effective mechanism to stop them. Blocking and banning them won't work. They will simply go make another account(s) and there are multiple ways to hide their IP from Wiki's CheckUsers (Wiki users with the rights to look at your IP and User Agent) available to them. Corollary--there is no effective mechanism to control the problem editors.
3) Wiki neither forgives nor forgets. Once a wiki target, always a wiki target.
4) Those with some sort of mental, medical, or social problem ("On the Internet no one knows you're a dog") can still edit wiki and the problems they have in the real world appear in their Wiki behavior, for example, the inability to work with others in a collaborative environment. Combine this with WIki's almost total ineffectiveness at controlling problematic editors and the result is that it is extremely difficult to free yourself from dysfunctional people/editors by refusing to try to control them.
5) Zealots of all types use Wiki to foment their favorite cause. This includes but is not limited to religion, geographic, and ethnic warriors. These users are known as "POV pushers" or "ethnic warriors" in Wiki parlance.
6) The WikiMedia Foundation (WMF) puts the brunt of the work of Wikipedia upon the volunteers. The vulunteers do almost all the article writing, handle all the dispute resolution (DR), including running the Arbitration Committee (AC or ARBCOM). AC members are especially susceptible to off wiki harassment. AC is also responsible for handling cases such as users promoting pedophlia on wiki, which is not supposed to be tolerated on wiki and can make AC members and others who fight them suspectible to real life legal issues, especially if they err and erroneously ban an alleged pedophile. Wiki's article quality would be greatly enhanced if more users had access to JSTOR, which requires a paid subscription. WMF designated user Raul6554, to hand out about 100 JSTOR subscriptions, but wiki has hundreds of thousands of active users--all at Raul654's personal discretion. The details escape us, but IIRC, he was mostly absent during that time and did not hand them out. This has been Raul654's pattern for years. He is also the "Featured Article Director", yet his last post was in February 2013--and prior to that he'd been largely MIA for over a year. So just how was he "directing"? Several months later and after a massive effort User:Bencherlite. Finally there was hope, but alas, not much changed, proving that old adage, "power corrupts and absolute power corrupts absolutely". As Bencherlite merely became "Raul II", running FA land as he sees fit, totally ignoring consensus and all.
All of this results in disaster: burnout, frustration, and a high turnover rate. The peak of Wiki in terms of new users, total users, and active administrators was in 2007. It has been in a steep slide in those terms and also become increasingly hostile to work in ever since.
This post by English Wikipedia User:Diannaa on 12 March 2013 is one of the all-time brilliant posts: "Never to forgive, never to forget? ''From Hell's heart I stab at thee? For Hate's sake, I spit my last breath at thee''? Is that the kind of wiki we want to be???"
WIKIPEDIA'S DECLINING EDITORSHIP
The main causes of Wiki's editor base, which has been nosediving since 2007:
1) The novelty of Wiki has worn off, ie, it's no longer new.
2) The low hanging fruit of fun, interesting, and important articles has been picked already.
3) Wiki has no effective mechanism to deal with the bullies, mental cases, POV pushers, or abusive admins.
4) WMF's and the developers' efforts/meme about increasing editorship is misguided. Adding facebooky notices (the red boxes) and the Visual Editor won't fix the problem. They are just putting paint on a house with structural problems. The developers' time would be better spent on making pages load faster and giving crats the ability to remove bogus blocks. The single biggest problem is item 3, just above this one.