I am the OP. Please understand that I am not against coding problems in interviews. Anyone who has done any interviewing will tell you that a surprising number of supposedly qualified applicants cannot code at all (usually because they have been doing project management for too long.)

And if you have a specific industry need to invert a binary tree or fill 8 containers with 32 differently sized boxes or whatever then go nuts. But I have found working through a 30 minute exercise with the candidate, asking them to explain their thought processes, and listening to what questions they ask is much better than just giving them 30 minutes to bash their head against a problem.

It is more effort for the interviewer though because it cannot be automated. But it does allow you to scale the interview by asking things like "What would it take to make your code thread safe? Imagine 4 threads. Now imagine 1000, what would you change?", etc.