Most Important Lesson in Online Marketing

I had a question come up yesterday, if I thought we could keep a marketing intern busy at our office. My response was "We can definitely keep an intern busy" then I proceeded to list multiple tasks that I do not ever get time to accomplish, like search tagging products and building reports. After that it got me thinking about what is taught in marketing classes at a University. Since I have a Computer Engineering degree, and my boss has a Graphic Design degree, I had to ask the only person in our marketing department with a Marketing degree. He told me that from what he can remember the most important thing in marketing was making money.
Now while I agree that making money is the primary goal of marketing, I don't think it is the most important lesson. Here is why, if you work for a company of any size you know that there are many different marketing channels. Now if the company is making more money which marketing channel do you attribute that increased revenue to? I think that the most important lesson in marketing is measuring results. Let me say that again, I think measuring results is the most important part of marketing. The reason I think that is without measuring the results of your marketing efforts you will never be able to determine what marketing channels and tactics are making you money. What you should know is that measuring results is not just how much money this marketing channel or marketing effort made your company, it is way more than that. Marketing results should be new customer percentages, profit and loss per new customer, conversion percent, average order value, percent of foreign revenue, percent of revenue from mobile, click through rate, and of course all the revenue metrics like revenue per blog post, net revenue, gross revenue and return on ad spend. Take this for what it is, I am not a long time marketing expert, but this is how I see marketing.