:::Isn't it likely (based on dynamic system theory) to be cyclical rather than terminal? Tinkerers mess about and degrade articles on WP until from time to time they get bad enough to irritate the experts who then fix them? I am reminded a bit of the famous (non notable) saw-tooth problem with the quality of management in companies. No one ever appoints someone taller than their intellectual armpit, because the new manager is always a potential threat to their position. So sires are succeeded by lesser sons or daughters until eventually someone is appointed who is so stupid they don't realise the threat and they appoint the best person. Hence the quality of top management in most really big companies (BP and the like) cycles, as do Wikipedia articles. It is true over a wider range of technical fluid dynamics ones and religious ones which I watch. The only exceptions are owned articles which have their own problems.