It presents a quick and easy, bullet-point spectrum of belief, which many people may not know exists.

An anecdotal data point: I linked to this quote when talking to a friend who was using me to vent their anti-theist ideas since they didn't have many other outlets for such thoughts. They laughed, and were able to properly categorize their beliefs (weak atheist) for the first time, rather than thinking themselves some kind of heretic (evil atheist).

That said, I didn't expect it to be this popular, either.