Interesting question, but to me, were I a founder, I would want to hire engineers who were smarter than me anyway, so I would have no problem giving an interview I myself couldn't pass. In fact, even as a regular employee I want to work with people smarter than I am. But it's still worthwhile to do exercises like this specifically to trigger one's empathy.
For a while, I stopped asking questions that I knew the answer to, and instead I asked the candidate questions that I was about to work on. So I didn't know the answer yet. It was the closest I could get to a normal co-worker situation, where we both discuss an ongoing challenge.
The only reason this approach is not scalable is that you need a constant flow of new problems, otherwise you start rehashing the same old questions, and by then you [think] you know all the good answers.
This reasoning is flawed. You'll have no way of knowing if your candidate's answer is actually correct (they may come up with a working solution that's different than your ore-canned answer), or whether they have a flaw.
The whole point of hard problems is to see how people approach problems - and having them identify their own mistakes and correct for them is part of that.
There's no flaw here at all. There are plenty of puzzles I have difficulty solving, but when someone shows me a solution, it's usually pretty obvious why it's correct and how it works.
Using this same principle though we can argue that someone who knows nothing about brain surgery, such as myself, is qualified to hire brain surgeons based on whether they can explain how to do it in a way that I personally think makes sense to me. I might like to commend myself for being able to hire brain surgeons by virtue of my own ignorance, but it seems to me that the flaw here is I don't really know whether what he explained is true, or if it just sounds good.
You can't make too big a gap--I certainly wouldn't recommend non-technical people trying to hire engineers this or any other way--but maybe it's still possible for a reasonably smart engineer to identify an even smarter engineer.
Because verifying an answer is easy, but creating it from scratch is hard. Analogous to this is intuition is that verifying a proof is simpler than coming up with the proof.
