Pay attention to what the author says about Marginal aMER. In my simulation / forecasting work, the relationship described comes through when measuring profit per new customer (though the relationship isn't identical to what is illustrated here).
P.S.: A reader recently responded that he wanted "more free stuff". If you are that reader, click on the link and subscribe to their free stuff.
P.P.S.: This is interesting. There is a clear relationship between giving away free insights and me staying in business. The relationship looks something like this ... the X-Axis represents the percentage of my blog posts where I give away my methodology for free ... the Y-Axis represents the percentage of annual income I generate as a result.
In other words, if I give away my methodology in 20% to 40% of my posts, I maximize my annual income. Give away everything in every post? I lose about half of my annual income. If I give you more free information, I eventually make less income and I'm out of business. Such is the relationship between a business and customers. Always remember that not all customers are customers ... some are consumers ... and there is a big difference. You make your profit off of customers, you generate improved vanity metrics from consumers.