Bokardo: The Del.icio.us Lesson:

The one major idea behind the Del.icio.us Lesson is that personal value precedes network value. What this means is that if we are to build networks of value, then each person on the network needs to find value for themselves before they can contribute value to the network. In the case of Del.icio.us, people find value saving their personal bookmarks first and foremost. All other usage is secondary.

As people use Del.icio.us more, and in order to gain more personal value, they use tags to be able to find their bookmarks later. Tagging isn’t even the primary function of Del.icio.us. Most of the tagging done on Del.icio.us is done secondarily, and for personal use.

The social value of tags on Del.icio.us is only a happy side-effect. Even though most of the ink spilled about Del.icio.us is about the social value, it’s really not the reason why people use it.

Similar to Google aggregating links that were originally created for taking readers from one document to another, Del.icio.us can aggregate tags in order to find out how people value content. If 1,000 people save and tag the same bookmark, for example, that’s a good sign that they find value in it. But to think that people tag so that this information can be aggregated is to give people a trait of altruism they just don’t possess.
Blinded by the Aggregation Light

Unfortunately, the ability to aggregate has blinded many software developers to think that tags are a cure-all to the success of their software.