the economic mechanism behind "captcha", and other verifications is to increase proffits by bleeding off relavance, a very litteral mechanical braking system, trading momentum for money, or money for momentum on a closed course. The ability to scale up friction is almost infinite and realy quite cheap, but humans are finnicky and also energetic, but the real threat to building a closed internet, is simply demand collapse. That the article is about adhesives, is a bit funny.