A good friend of mine who I highly respect (@markwylde) suggested to me that instead of having a CAPTCHA on the Registration view, we instead use a PoW (Proof of Work).
See linked article above.
Here's a demo of one I found: https://git.sequentialread.com/forest/pow-captcha
The only downside to this is it obviously requires Javascript.
So... What if we instead just have a hidden input field, a "honey pot field", that if filled out we assume the agent was a bot? A human would never fill it out, because it's well umm hidden 😅
This is relation to this issue