Wikipedia:Wikipedia is not just an encyclopedia
In an article on itself, Wikipedia is described as "a free, multilingual, open content encyclopedia project". A phrase commonly shouted out in meta-discussion is "Wikipedia is an encyclopedia". Although true, Wikipedia is not just an encyclopedia, but is also a project to build an encyclopedia. There's no problem with doing things on Wikipedia that aren't immediately about the articles, as long as they are in the interests of the project, which is building an encyclopedia.
It's not a traditional encyclopedia
Wikipedia wasn't the first digital encyclopedia, and won't be the last. It is, however, not a traditional encyclopedia. This means it can't be picked up off a shelf, flicked through, written on (though it can be vandalised), torn, worn out, get outdated, etc. The articles are as good as preserved forever, and can be copied and backed up easily. Articles can be updated instantly, and everyone will be able to appreciate the new information instantly. Hundreds of new articles are created each day, and can be seen instantly. What is best though, is Wikipedia is free, and can be redistributed at no cost. Paper encyclopedias on the other hand can cost a lot of money.
There are currently 31,414,838 registered accounts, plus millions of IP addresses. That's a lot of authors, even if they haven't all made an edit. The truth is, we don't know how many authors Wikipedia has. Even more importantly, most of Wikipedia's authors are anonymous. Due to Wikipedia's nature as a wiki, anyone can edit the pages, which means the number of authors has no upper limit.
There is a community
As with other encyclopedias, articles are worked on collaboratively. Since the early days of the Internet, there have been online communities, from newsgroups to chat rooms to social networking. Inevitably, Wikipedia has a large community. This means there are going to be lots of discussions, both about articles, and about other aspects of the encyclopedia. Wikipedians are, in fact, human, and Wikipedia is not just an encyclopedia. People are therefore allowed to discuss things that don't directly affect articles. Such activities are desirable as long as they contribute to an atmosphere beneficent to improving the encyclopedia. For example, if people enjoy spending time on the site, they may be more willing to do menial tasks like rolling back vandalism. In this sense, maintaining a friendly community may have a direct impact on the man-hours spent doing constructive work in the interest of the project. However, as soon as such community-building activities become an end unto themselves, and tend to impede rather than encourage work on the project, they are to be discouraged.
Not everyone is good at writing articles
Not everyone can write articles. Some people are better at other things: some are good with template code, some with images, some with finding references/typos, some are good with bots etc. Each person has an ability. There are areas on Wikipedia that aren't about writing articles. This essay is an example of that. If people want to do important work for Wikipedia that doesn't involve articles directly, there is a wide choice of tasks they can usefully engage in. A summary of such tasks can be found at Wikipedia:Maintenance and Wikipedia:Patrols.