I'm not the one to ask. Isn't what we're doing right here on HN similar if not identical to "blog comments"? We have read an "article" (or "post") and now we'

I'm not the one to ask. Isn't what we're doing right here on HN similar if not identical to "blog comments"? We have read an "article" (or "post") and now we're commenting on it. So it seems to me at least one person has designed a system that allows this and keeps out spam without using a CAPTCHA. Consider this: CAPTCHA is prohibiting comments based on the manner in which they are submitted. But what are really trying to stop? "Spam". How do we know what is "spam"? We look at the content. It might be hard to define "spam" because it is a subjective determination. But we know it when we see it. What if someone writes some interesting content that is "not spam" but wants to submit it in an automated fashion? CAPTCHA stops him from doing that. CAPTCHA stops automation. It may stop spam. Or may stop something else. That's my issue with CAPTCHA. It is not aimed at spam, at least not directly. It is aimed at automation.