In what sense is there a certain "amount of work to do" defined independently of the number of volunteers and their interests?
The only thing I can think of is that as the wiki grows in size, the amount of work that needs to be done to maintain fixed quality (combating vandalism, counteracting normal decay, fixing link rot) goes up roughly proportional to the number and length of articles.
I guess you mean something like "Wikipedia ought to have an article on X, and didn't in 2007 but does in 2020". That certainly tracks the fact that there was more low-hanging fruit in 2007, but I don't think writing that article means there's any less work for a fixed number of editors to do. The amount of work left to do -- between here and a complete encyclopedia of all human knowledge -- is damn near infinite, and is limited mostly by editor interest.
Wikipedia's rules on notability and article length prevent it from growing infinitely (in theory). So my point is exactly that - all that "low-hanging fruit" is mostly gone, and most of the actual writing work that's left is either writing a new article on a subject that is at the margin of notability, which one would expect the average adult to have less interest in than writing a new article on a truly notable subject, or rewriting a section of an existing more notable article which tends to annoy whichever editor last edited it.
But you make a good point that the maintenance work probably grows linearly with the size of the corpus, so really the flat number of active editors shows that the number of editors actively engaged in the research and writing of entries has probably actually declined significantly since 2007.
> Wikipedia's rules on notability and article length prevent it from growing infinitely (in theory).
I take your point, but I would claim that Wikipedia is no where near the maximimum size set by the notability criterion. You can just look at the incredible depth it has on some niche topics like anime that happen to be of interest to the editor demographic (which do strain the notability criterion) and imagine that level of thoroughness on lots of other stuff like (e.g., "photobiology" is a weak page that came up hitting the random-article button).
> so really the flat number of active editors shows that the number of editors actively engaged in the research and writing of entries has probably actually declined significantly since 2007.
Yea, maybe, although improvements in automated maintenance tools may mean that a fixed or even decreasing number of editors could be maintaining the growing encyclopedia.
> Wikipedia's rules on notability and article length prevent it from growing infinitely (in theory).
That doesn't appear to be true. New people are born, new events occur, new things are discovered, and new entertainment is released every day, all of which increase the pool of eligible topics on Wikipedia. As long as history continues to be made, new articles will continue to be written.
Companies, sport, politics, arts, endless churn. It's not unusual to find out-of-date articles on Wikipedia. It also seems to be that a surprisingly small proportion of edits add new information.
As an English Wikipedia user, one obvious gap I've noticed is the lack of detailed information about the geography and history of countries where English is not natively spoken.
I can only imagine that as time goes on, more of these details will be filled in!
