Google will supply the commercial results, but not all of the world's information - only its most profitable information. If you want to know how to do something, how something works, you'll use a different, non-google indexer for searching, say, all of the "how to" sites: e.g. wikipedia, stack exchange, about.com, etc.
I've gradually started to do this using DuckDuckGo's bangs [1]. It actually works pretty well if I know exactly which site I want to search. I do miss Google's ability to filter by time, though.
Nevertheless, I wanted to take the time to thank you for your information about DDG's bangs. I've been using DDG since Snowden, but didn't know bout bangs! Looks very useful and shorter than typing "site:" in google. It kind of reminds me of multireddits