Yes, this is good advice. I think what's important to focus on here though is not necessarily that it's anti-marketing or anti-monetization. It's against making money by capitalizing on whatever is populat, and in favor of simply being successful (which can include making money - perhaps lots) at what you're really good at or interested in.
Really it's just acknowledging that content is king, and if you do what you enjoy and are good at, generating content around your real interests and knowledge, then people will probably appreciate it. If you are doing something for everyone else, you either get very shallow interest, or quick interest that doesn't last, or most likely none at all. People are interested in opinion, perspective, passion. If you are passionate about something, express it. Likeminded people will gravitate to that.
I guess another important part of this then is "don't care about what people who aren't interested in what you're doing think". In other words why should you care what Joe Public or the mainstream think if you want to blog about the best way to write a cross-platform random number generator? Care about what people who also are interested in that subject think, and chances are those people will come to you to talk about it if you express that interest. Increasing market share and readership is only relevant to the degree that there even is a readership for your given subject.
Unless you happen to be blogging about the latest Britney Spears gossip chances are your market is going to be a tiny fraction of the general public, so don't sweat it too much.
So in short, I agree.