[olyjohn]

I get hit with them all the time. That doesn't answer how does a human abuse a website? Hitting F5 on the keyboard 1000 times?

[chrismorgan]

Abuse isn’t just about inducing CPU or network traffic load (in fact I doubt that was even considered when CAPTCHA was first invented). It’s spam, fraud, that kind of thing. A lot of it is bot-perpetrated, but quite a bit is by humans too.