I'm not sure if you know this but as vast as wikipedia is, its content probably accounts for far less than 1% of the historical content that is out there.
A front line historian distills tens or even hundreds of thousands of pages into a lengthy dissertation or book. That document is likely too dense to be of much interest to you or I. But another historian writing popular history books might reference it and also use some of its citations to quickly find interesting primary sources.
In this way, a 500 page popular history book may be distilled from a hundred other 500 page books which themselves are distilled from thousands of pages of primary source material. Wikipedia is an online encyclopedia, not an archive. So it's not really the appropriate place to house anything but the most distilled of these products. Essentially, all the other material is not relevant. But it's necessary to produce the relevant stuff.
As an example, you can read the wikipedia on Lord Nelson. You'll find most of his major life events listed there. But if you buy even the lightest biography on the man you'll find much more. Why? Are the people curating Lord Nelson's page lazy for not including those details? Of course not. The Lord Nelson page is probably obnoxiously over edited. But there is probably more of a fight about what not to include than what to include. Because the article seeks to be a relevant encyclopedia entry not an exhaustive resource.
My town's coal mine history may warrant a brief mention on wikipedia but not much more than that. However, if someone were to start composing a book on say labor organizing in Western Washington state, they might be interest to consult our archive and the distilled work our historian has done. More importantly, if a historian invented an interesting mode of statistical analysis, having that raw data already partially curated could move them a long way forward. This happens pretty often. A historian comes up with a novel way to count some interesting historical phenomena and they can only do it because some enterprising local historians whiled away hours collecting specific relevant information.
Intesting discoveries about historical economies come from counting of mills and bridges and other mundane activities. The path travelled by important historical figures come from historians stitching together news items and diary entries gathered by a local obsessive historian. And so on.