My family has a running joke that the road signs in Ireland are there to remind you of things you already know rather than to direct you to places you've never been. If you've never been to Ireland you'll think I'm exaggerating, but the signs really are just a step short of saying "the place where Mary brought that lovely jacket - 12 km".
It's even worse if you stop and ask for directions - "Oh, you'll be wantin' to take that lane just past Brian's house, you know, Brian with the dog!" It takes about fifteen minutes to convince your erstwhile directioneer that you don't in fact know Brian, having spent the majority of your life on the other side of the Atlantic Ocean, and that you'll really need your instructions expressed in a format that doesn't presuppose knowledge of the local geography so intimate as to render directions unnecessary. At which point you'll be given a confusing array of rights, lefts, and reverses, followed inevitably by "and then it's right up the road, you can't miss it!", which you'll dutifully follow in a large circle before returning, six hours later, to ask the exact same gentleman for directions.
In general he'll pretend to have never before made your acquaintance and eventually (after repeating the previously-rendered fifteen-minute protestation of your non-acquaintance with Brian's dog) give you an entirely new and completely dissimilar set of instructions that will culminate in your accidental arrival in Paris.
I'm not entirely sure how one manages to drive from Ireland to mainland Europe, but it happens, I swear.
But anyhoo, my point is that Irish road signs are designed to remind you of things you already know, or provide you with details about subjects on which you already have high-level understanding. And Wikis are exactly the same way; they make excellent references, but they're largely terrible as first-order sources or methods of communicating information, primarily because of the structure they inspire - the same disaggregated, freeform organization that makes it possible to deep-dive into related matters as a reference makes it very difficult to arrange information in the sort of cohesive sequence necessary to teach people something new.
Learning something new is akin to recording every lecture in a college course and playing them back in a random sequence - even though every note may be hit, it's not precisely musical.
All of which means precisely nothing, except that I haven't posted in a while and this was the only interesting and non-proprietary thought in my head.