Interesting interviews from Google, Facebook, Microsoft gets reviewed and talked about frequently by my friends and colleagues. I did not know that interview process should remain confidential.
In this case, the worry is that candidates will see common interview questions in advance. It's an open secret that most interviewers at most companies reuse interview questions to a ridiculous degree.
The right answer is to fix that, probably. Glassdoor is going to change this over time whether we like it or not. But the traditional answer is "crack down on people talking about it."