Ok this is a genuinely perfect way to research an entire field by article instead of having to jump recursively link to link and forgetting what you were doing 5 minutes ago.
I've never seen wikipedia from this categorized vantage point. If we're being real their UX is kinda crap outside the usual search->article->link flow and could use a complete rework.
Lucky 10000?
Three tricks if you didn't already know:
1: you'll find categories at the bottom of regular mediawiki pages
2: if you click one, you'll end up on a page like eg. this: https://en.wikipedia.org/wiki/Category:Computers
3: the tree style tabs plugin in combination with middle-click is criminally underrated for navigating hierarchical data. (middleclick open-in-new-tab is only mildly handy, tree style tabs seems tepid by itself without it)
TIL, I think I've landed on these pages a decent number of times but never from wikipedia's internal nav. I assumed they were more of an adhoc occasional thing, not a standard for sorting all pages.
Oh, right, and I forgot about the tree views!
The little arrows next to the subcategories can be clicked to open up trees, so you have hierarchical data in there as well. Try click open eg Classes of Computers (With 41 direct subcategories, and 91 pages directly in the top level category, that's a big tree!)
Categories are criminally under-used.