[ahoyhere]

Speaking is also about changing minds and hearts. Persuasion works much better in person than in print. There are studies to this effect.

The effect of a talk does not have to "disappear rapidly" after the talk is over. That is why you will find lots of old Jobs keynotes on youtube, because they are still very powerful, and useful, interesting, educational, and motivating even when the products discussed are no longer being sold.