Nothing, they're a good solution for this company. My point was the conclusions were based on this company, not everyone who suffers spam, the article has since been updated with:
> For some reason this article has hit the front page of Hacker News and is getting quite a lot of traffic. I should mention that yes, I acknowledge CAPTCHAs are of course sometimes unavoidable. That doesn’t mean, however, that we should ever feel good about using them, nor should we fool ourselves that users don’t mind them.
Which was my point. When spam is a serious issue then captchas are unavoidable 99% of the time.
If you're site is running on a popular forum software, robot-only inputs and timestamp analysis would eliminate most of your problems.
Spammers are probably not targeting your website in particular, rather the software your forum is run on. If you add atypical anti-spam measures you'll separate yourself from others using the same platform, defeating the typical phpbb or vbulletin bot which probably accounts for most of your spam.
> For some reason this article has hit the front page of Hacker News and is getting quite a lot of traffic. I should mention that yes, I acknowledge CAPTCHAs are of course sometimes unavoidable. That doesn’t mean, however, that we should ever feel good about using them, nor should we fool ourselves that users don’t mind them.
Which was my point. When spam is a serious issue then captchas are unavoidable 99% of the time.