Must be an SV thing? I've never been asked to recite a mission statement for a company where I was interviewing (or even working at, for that matter). Most assume I don't know much about the company and a good part of the introductory chit-chat in an interview is them telling me about their history and what it is that they do.
I live in the bay area and have worked for several of the big tech companies and startups. The only time I can remember anyone discussing mission statements was when I interviewed at AirBnB. They had a full interview (30 mins IIRC) just about the company mission. The explained that it was very important to the CEO. I apparently failed that interview and they made me do another with a different person about the same topic. It was very awkward.
