Spam and the survival of the fittest
But while the marketing world has evolved in the same way, it is as full of beautiful, immaculately targeted campaigns as the natural world is of cute animals. For every bird of paradise, there is a bug somewhere, living out its ugly existence because it suits its environment. While we have superb levels of creativity and innovation, we also have spam email. Why? Because it works. Spam is cheap to implement and requires tiny returns to make it viable. The business model is successful. Spam is unwanted, ugly and morally questionable but it is not inefficient.
Luckily, this same environment is driving the evolution of worthier techniques, such as search engine optimisation. We may hope that firewalls and legislation may combine to alter the environment further and eventually drive spam out of existence. But for the moment, we shouldn't be surprised at the number of unwanted emails we get every day. It's only natural after all.