Funny enough - I actually wrote a [cathartic] short essay on that very concept a few months ago when I was being buried alive by captchas. I called it 'Blood for Access: An Alternative Approach to Circumvent Captchas'.

Here is an excerpt from the final paragraph:

In conclusion, the current state of captchas deployed across the internet can be frustrating and exclusionary for many users. My proposal for a blood-based authentication approach aims to highlight the absurdity of captchas and advocate for a more user-friendly and inclusive internet experience. While there may be challenges in implementing this approach, the potential benefits in terms of improved user experience and inclusivity make it worthy of consideration. It's time to explore alternative methods that prioritize user accessibility and convenience while maintaining security, and blood-based authentication could be a step towards a more inclusive internet for all users.