> Trying to collect pages is annoying ugly; about the best you can do is with "categories."

With vanilla mediawiki, sure. If you use Cargo or SMW, you can do pretty much anything you want, especially with Cargo. Add in Lua (Scribunto extension) and you have effectively a full extra layer in your stack.

(There's also DPL (Dynamic Page List extension) as an option; if what you're doing is easy enough to express, and you're just trying to build lists of pages, you may be able to get away with just doing DPL queries and nothing else beyond that.)

It might be more technically complex than you want it to be, but it's definitely not limited to categories.

I enjoy Cargo and DPL, they're powerful and great tools for automatically aggregating and filtering content, and I used both of them a lot at a MW that I was an admin on for several years. But it still isn't easy to build an ordered, hierarchical, book-like structure with book-like output, which was a constant request. It wasn't just technically complex (no users wanted to learn how to do it, they wanted one person to do it for them), it also didn't do the one thing most people wanted it to do.

The Collection extension did that, though, but Wikimedia's weird behavior around it and their multiple failed attempts at choosing a tech stack for output — OCG/ZIM, PoD/PediaPress, Electron (not that one)/Proton — much less the next step of building that functionality into a usable feature in MW, turned me off from trying.

I need to dig into BookStack (I imagine like most wiki flavors, it'll lack the templating features in MW that I rely on), but the fact that it's built on the book/chapter paradigm from the ground up instantly catches my eye.