I disagree, as long as getting the right answer isn't important. I flat out tell people I don't care if they get the right answer, that I just want to hear their thought process.
Such questions used in this way are extremely valuable.
I do the same thing. It's how the thought process works that's interesting, not the result. There is no problem or teaser whose answer is both short enough to be devised during an interview AND is representative of how a candidate would perform in real projects. Our field deals with complex systems in many dimensions.
Instead, looking for how a candidate approaches a problem, do they just go for the obvious solutions, how creative will they go, any experience they can draw on, how well they overcome unknowns, etc.
It's how the thought process works that's interesting, not the result.
I wonder how many interviewers have the necessary background in clinical psychiatry to analyze a candidate's thought process, or if that's just more handwaving away hazing.
If the candidate is applying for a job which will require the ability come up with solutions to new and/or difficult problems while under pressure, sure. Why wouldn't the prospective employer want to explore that at interview?
Such questions used in this way are extremely valuable.