> If you can describe the day-to-day of what we do without much prompting that's a very strong signal you're a good fit
Why not just ask that then? "Tell me about yourself" is just a bad open-ended question. I've been in enough interviews to anticipate generic bad questions like that or "what's your biggest weakness" style questions, but not everyone has.
Hiring managers frequently can't differentiate between people who are knowledgeable and people who are just good at interviewing. I've coached many of my peers and done lots of coaching with success because at the end of the day, interviews are about taking advantage of the information asymmetry between your actual experience and what the hiring manager can actually know.