Good point. Maybe I'm unusually generous, but when I'm in the interviewer seat, I generally try to steer candidates into territory where they can succeed. I want to give that "hire" recommendation! But I need pull enough signal from the noise to be able to support that recommendation, and ultimately I need to measure that signal using the measuring stick defined by my employer. If I didn't need to conform to that measuring stick, I'd just do interviews that were casual conversations about projects. But I need to ask certain types of questions to measure certain dimensions.
The "tell me a little about an interesting problem" question is usually there to gauge your ability to summarize a cool problem and solution down to to an appropriately sized story. Sometimes when I ask this question, candidates just launch into stream-of-consciousness expositions, talking just-in-time as the details come to their brains. At the 2 minute mark, I start thinking come on, don't do this to yourself. At 5 minutes, I will gently try to hint to the candidate to try to summarize and wrap it up. Some people just try to fill every silence with words and I have to finally firmly yank them back and cut it off. I hate to have to do it, but if the candidate can't time-manage the answer, I have to time-manage the questions.
The "tell me a little about an interesting problem" question is usually there to gauge your ability to summarize a cool problem and solution down to to an appropriately sized story. Sometimes when I ask this question, candidates just launch into stream-of-consciousness expositions, talking just-in-time as the details come to their brains. At the 2 minute mark, I start thinking come on, don't do this to yourself. At 5 minutes, I will gently try to hint to the candidate to try to summarize and wrap it up. Some people just try to fill every silence with words and I have to finally firmly yank them back and cut it off. I hate to have to do it, but if the candidate can't time-manage the answer, I have to time-manage the questions.