Describing how it works and using it to troubleshoot real problems and drawing the correct conclusions are very different things. If you believe it is simple then you have a shallow understanding of traceroute, which is why it's a good interview question as you can go really deep on your answer.
Even seasoned network engineers get it wrong.
https://youtu.be/WL0ZTcfSvB4?si=dtihJG1pGJwiyj1u