I don't see how captchas "just make sense", especially in the most common image-based incarnation. I have worked with visually impaired people and the most popular request was always "I want to something on this website, but they have a captcha I can't see (and occasionally an audio captcha that makes no sense), can you sign me up/comment for me/do whatever task?".
As a sighted person, I've even run across captchas that were impossible to decipher, both from some third party solution and from something like recaptcha, the latter which bothers me to no end because sometimes both words are ambiguous.
Whether or not they make sense depends on your audience and your site and your implementation of it.
As a sighted person, I've even run across captchas that were impossible to decipher, both from some third party solution and from something like recaptcha, the latter which bothers me to no end because sometimes both words are ambiguous.
Whether or not they make sense depends on your audience and your site and your implementation of it.