If you wanted to work for an organization where everyone likes to show off their skills to one another in the interviews, you'd have gotten the job, and you'd be one of them.
The best interviews I find are like a first day of work (but unpaid). Your experience and skills are established by resume and portfolio. The interview shows whether you can work with the team and wrap your head around the org's problems. If you're having to show off- well, that's how your work will be, too.
Google's interviews convinced me, years ago, that there's no way I'd ever want to work there. And that feeling hasn't changed one bit. Much like FB, it's an org whose coding needs are really pretty trivial and the real work was done and finished a long time ago (but there's plenty of need for debugging, egos especially). If you want to work there and surf the gravy train, cool for you.