On the flip side, an interview where you're doing relevant work with another engineer is a way to evaluate whether you're a decent person to work with. I've hard-passed on candidates with immaculate resumes and huge open source portfolios because they were rude and insufferable. When you're hiring, you're building a team, you're not hiring individuals who work in isolation.

In a previous life, I was forced to work under a very senior engineer who was/is a well-known thought leader with a handful of books published. His leadership was nothing short of abysmal: he had no people skills, answering questions with links to e-books he'd written for O'Reilly in lieu of responses. The best engineers got tired of being micromanaged and nit-picked and left. It doesn't matter how smart you are if the other people at the company hate working with you.

There are many coding interview objectives (and I won't defend interviews which try really hard to ensure you know how to code) but pair programming and systems design questions are absolutely necessary to understand whether the person you're hiring isn't just qualified, but rather the kind of person who will make the team better overall.