This has been pitched as an idea in the past; I don't think it really took off then either.
One of the problems is that users have become accustomed to skipping over ads - they either miss the captcha entirely first go (not great) or get put off by having to engage in the ad (also not great).
One of the problems is that users have become accustomed to skipping over ads - they either miss the captcha entirely first go (not great) or get put off by having to engage in the ad (also not great).