Here's reality: Someone who knows their stuff is able to dive into details of their work in a way that an impostor can't.
My response to the above would be to have the person bring in some of their work and take an hour or two to take a deep dive into it. I want to see code, documentation, examples of trade-offs and a discussion of the reasoning, challenges, what could be made better, what should not be touched and why, project history, etc.
A conversation with someone who knows what they are doing and is very actively involved in their work is very different from a conversation with someone who might be trying to bullshit you or simply doesn't know enough.
I hate puzzles. All I learn from them as an employer is that someone might have devoted a month to memorizing a whole bunch of them for the interview.
I would imagine that at the scale of a company like Google, resorting to puzzles as a first filter might be an inevitable reality. If you have to interview people en masse you almost have no choice. It's like Stanford having to filter through 40,000 applications a year to accept 2,000 students. You have no choice but to go algorithmic on that problem.