Comment by 4midori

In many cases, I believe it is. Consider Tim Ferriss' book 'The 4 hour work week' for example. It had lots of creative ideas, and many folks used them successfully. But by the time the book was published, the market had changed. Google Adwords used to be Hella cheap, which is part of what enabled methods described in the book. But they're not anymore, and there's too much of everything.