[mike_hearn]

The big networks don't use CAPTCHAs in the original sense they were meant to be used anymore. They all moved on to phone verification many years ago. I was a part of some of the discussions in Google on this issue - should we keep using CAPTCHAs at all given that they'd been basically replaced by better systems?

The answer was yes. CAPTCHAs are still present because they act as a throttle. The point of a strong CAPTCHA is to limit the amount of abuse that can get through if the other mechanisms break down, by exploiting the fact that humans are kind of slow. Even though OCR can handle most CAPTCHAs these days, it's still not 100% effective, so by ramping up the number of CAPTCHAs you ask users to solve you can still put a throttle on activity. In this way it acts as a last line of defence.

That's why I'm not sure this is going to work out. CAPTCHAs are not a way to distinguish good users from bad, which is how CloudFlare is trying to use them here. CAPTCHAs are way to slow down and throttle traffic that might be auto-generated when you can't tell if it's good or bad. Building a new way to show you solved a CAPTCHA previously doesn't help if the reason you're being shown CAPTCHAs is specifically to slow you down regardless of whether you're good or bad.