It's not just the void: it's the fact the arrow points directly to the link in the top banner ad.
It's also almost perfect for the audience: it's aimed at cartoonists where intentionally crude stylings are usually intentional.
(I doubt it would be similarly effective if promoting SaaS or luxury travel, where it would look jarringly out of place)
It also has a much higher proportion of screen real estate than the average banner campaign and apparently little of visual interest to compete with it, both of which are critical to its success.
It's also almost perfect for the audience: it's aimed at cartoonists where intentionally crude stylings are usually intentional. (I doubt it would be similarly effective if promoting SaaS or luxury travel, where it would look jarringly out of place)
It also has a much higher proportion of screen real estate than the average banner campaign and apparently little of visual interest to compete with it, both of which are critical to its success.