Not sure why you were downvoted, to be honest, because I think this is a reasonable take. I don't prep for interviews (or, these days, for sales discussions), except to read about the company and to consider how my skill set can help solve their problems.

Google's insistence on this preparation thing is doubly weird to me when I consider that literally nobody "prepares" for work every day in this manner; knowing what a developer can do after studying his brains out regarding things that will be ejected from the brain again immediately after the interview doesn't really send a meaningful signal.