It just seems like the perspective is off. Implementing some script which reads images of the website which depicts the CAPTCHA, sending it to some AI-solution which can succeed some percentage of the time. Adding this to something which can interact with the website (not sure if you’ll need to indirectly act through something like selenium or if you can make direct web-calls), while also ensuring that the CAPTCHA doesn’t receive other suspicious data.
If you go through that trouble, I would be amazed if combining 2 or 3 words from a dictionary into a username would be the kryptonite of your bot farm.
Again, I don’t know, and it might be a much more preventative solution than I can understand, but it feels like a strange security by obscurity.