Quartz has an article about a relatively small on-line encyclopedia of philosophy at Stanford that manages to accomplish the complete trinity of being authoritative, comprehensive, and up to date. Other on-line knowledge sources only manage to hit one or two of those. Wikipedia, for example, is only up-to-date, not authoritative or comprehensive; Quora is only comprehensive, not authoritative or up-to-date. (At least, according to the article.)
How does the Stanford Encyclopedia of Philosophy accomplish this? Mainly by picking expert contributors carefully, having them write self-contained entries, and requiring them to update their entries every four years. Ta-dah, expert knowledge source!
The thing is, while this is a great idea for a 1,500-article encyclopedia focusing on a relatively narrow field like philosophy, this isn’t really an approach that would work for something intended to be bigger and more general. The article dances around this, but doesn’t really ever come right out and say it. Inviting expert contributors to write every article just doesn’t scale to something the size of Wikipedia.
Even so, the approach does stand in sharp contrast to the actual hostility Wikipedia has demonstrated to expert contributors. By focusing on just one area of knowledge, the SEP has managed to avoid the flaws in Wikipedia for that one area of knowledge.
Perhaps this is the true solution to finding expert encyclopedic knowledge on the Internet—to remember that Wikipedia is by its very nature extremely general. If you want more expert knowledge, looking at a narrower subject-matter encyclopedia might be more helpful, just as you’d look at a fan wiki if you want more detailed knowledge of some particular TV show or novel series than Wikipedia can contain.