You must not have read very carefully then. From the article:

It’s important to note the way reCAPTCHA works. Each user (or bot) is presented with a control word, and a word unrecognized by OCR. This control word is already known to Google (who runs reCAPTCHA). If you get this first word right, it is assumed that you get the second word correct as well. So, in reality, you only need to guess the key word correctly.

The author explicitly addresses your point and if you looked at his examples, most are very difficult for both words. In many of his examples, the control word is distorted beyond reasonable recognition, and the new word is cut in half or worse.

Actually, reCaptcha requires a specific word to be correct. Specifically, the illegible one.

The article does make this point.

You must have missed the part where he tried to guess with the easier of two words and still failed. The control words are rarely any easier to read than the unknown word.

Your original comment said that the biggest problem was home-grown captchas, and that people should use something established like recaptcha - the article was specifically complaining about recaptcha.

After your 'edit' my comment makes no sense.

I don't want to spend more than a second or two working out what a captcha says - if it wasn't something I absolutely needed I'd probably have gone away long before the author's patience ran out.