Nobody is claiming it's perfect. But notice how nobody here is analyzing why people use ReCaptcha in the first place nor providing alternatives.
If you knew nothing of ReCaptcha and only read these comments, you'd wonder if it was a gag website operators put on their website for self-amusement, which is basically how I looked at homework as a kid. But I feel like this discussion is a bit more one-sided than I expected on HN, a place where I would've thought more people had experience running a website and how immediately effective ReCaptcha was the second you added a <textarea>.