Most of the core knowledge I've learned over the years as been self-taught. I love the challenge of picking up a new programming language or software and simply learning it inside and out, but not everyone is able to extract this knowledge as easily.
Today, in the information age, with rapidly growing technology connecting everyone, we can learn almost anything on the internet. But there is a lot to be said for information that simply can't be learned from an online pre-recorded video, electronic book, web help page, or even blog - things like troubleshooting that only come through experience, for example. We can document common issues, provide known solutions, and dump our knowledge into it, but often it's all missing a key element.