It really annoys me when companies I do business with make me do extra work for Google by employing reCAPTCHA.
What would once be a certain no, I now question whether google is actively weaponizing reCAPTCHA in the new browser wars. After all, Chrome has such a large market share in the right places that I'd be surprised if the model didn't take into account user agent to determine non-automated users.
The worst pattern I'm seeing now is when login forms decide to add it after just one incorrect password attempt. I completely understand registration forms -- but login forms?
Limiting the number of errors before sending a link to reset your password (for example, I agree there might be different ways to deal with that) is no rocket science, and being dependent on third party for such a trivial thing is, in my opinion, a bad idea.
Rate limiting alone isn't a solution. But it can be part of a solution that doesn't require reCAPTCHA.
> If you lock people out after a certain number of failed login attempts, you allow an adversary to DOS your users by constantly trying to log in as them.
That isn't how the pattern works. On next successful login you basically inform the user that they need to confirm it's them with an email token. It works well. ReCAPTCHA doesn't.
I can only hope that firms will eventually figure out that reCAPTCHA is a bad user experience.