I would be willing to best that a lot of people here started direct linking to affiliate offers at the very beginning. For the most part, people that are new do this because it's easier. No setting up a webpage, squeeze page, autoresponder, follow-up campaign etc. The problem is, you never get any lifetime value out of the traffic you are generating. Why would you want to spend hours and hours writing articles, doing keyword research, backlinking, so that you can get a person to visit your site 1 time.. Or even worse, spend tons of money on advertising to monetize a buyer only one time!
This is not to say that you can't be profitable doing it, because like many others I have. But I'm talking about building a sustainable business. Every now and then I will direct link to test a new offer and see how well it converts. The bulk of my business is dedicated to capturing data. There really is no debating the fact that a subscriber is much more valuable than a visitor.
My advice is this.. If you are not doing anything to capture data, start doing it now. Margins in this business are becoming smaller and smaller, and if you want to survive you have to get the absolute most out of the time and energy you are spending. For affiliate networks it's easy money, and most of the time they are capturing leads from the time/money you spent to send people there.