Isn't this a typical Quora answer? Full of filler and shitty hard-to-verify details that provide no value to the answer ("the language is encrypted twice", what the hell), and very little effort on answering the actual question (what is the purpose of CAPTCHA).

And the community rules try to block people from writing firm "you're full of shit"-like answers, even though every other answer of Quora is full of lies like "Linux is fast, because it was designed for 16-bit computers".

The answer is not just fluff. It for example links to https://github.com/neuroradiology/InsideReCaptcha where you can read more.