While I agree that WikiPedia is unnecessarily restrictive in their coverage (particularly with regard to how to
do things), I think there's a lot of value there, too...especially in a world that has lost access to anything more in-depth. I mean, I can go to WikiPedia and figure out how ancient peoples cooled and heated their homes, handled irrigation, preserved foods without refrigeration, what plants are edible, what plants grow in what regions (though this would be thrown off by a climate catastrophe), how to render fat for storage, how to make rubber, how to smelt iron, how to build a boat from naturally available supplies, how to make cloth water resistant, natural remedies, etc. While it's not a "how to" guide for any of these things, if you can read, look at the diagrams, and follow the references within WikiPedia, you can figure it out with some trial and error.
The premise isn't that the folks with WikiPedia can rebuild modern society. It's that they literally can't (even if they had better knowledge resources), but would still have a survival advantage from having a little bit of the old knowledge. The fact is that if we lose our modern society, we'll never be able to build it up again. We've dug up all of the easily accessible resources, already. Scavenging from the good old days is the best any post-apocalyptic society can hope for, as bleak as that sounds.