That's one datapoint. The counterpoint is the thousands of forum owners who mistakenly relied on captcha to prevent spam at the expense of other antispam measures, like GeoIP.
I'm not saying captchas are a magic one-step solution to end all spam (hence the mention of Akismet). I'm just disputing the idea that they are "nothing more" than illusory security. Sure, they can be turked, and sure, if someone relies only on captchas they'll probably eventually get screwed. But they do provide some benefit as part of a complete approach against spam, in that they raise the cost of a spam attempt up from zero. Unless you have meaningful levels of traffic, the vast majority of spammers aren't going to bother with you if it costs anything at all to hit you.
