At least with simple "mother's maiden name" type questions, you could, if you were concerned by its insecurity, choose to use a secret value. With the automation of the process, that is not an option, while the security value of this pseudo-secret information will be eroded by its inevitable over-use.
I have both recorded in password vault and both are random.
The benefit is it they've reset my password for some reason or it was hijacked. I've been able to recover accounts. Not because I forgot a password but because it was essentially a harder to change 2nd "secret"
That is, indeed, the problem that these questions are supposed to avoid, but they only offer sort-of security to the extent that the information is sort-of confidential. Anything that the automated validation service can find from public sources can also be found by the black hats, and the more common these automated services become, the more worthwhile it will be for the black hats to similarly automate their search for them.
The end result is that real security that is based on something you know has to depend on secrets.