Good question. The jury might still be out on this one though. You could argue one way or another, as it depends on what is your definition if advertising. Advertising is not art but the industry used to have its share of regretful artists. Some artists in the 20th century, like Andy Warhol, made publicity the whole point of their art. It is common for film directors to raise money trying their hand at advertising before shooting features.

Despite the poor reputation of advertising in "art" circles, quite a few visual artists blurred the frontiers between the two. For craftsmen, it doesn't matter as long as they can use their skills to make something—and they need the money, too. I understand the bad rap advertising gets, especially online, and wonder why it is still seen as the dominant revenue model on the web. Still, I'd love to read cases of significant artists who used advertising to fund their art.