It's only one way to approach things. Many good people are not great explainers. However, I do find a willingness to try and get down to first principles a good sign. I only take it badly when people seem unable to think outside their expertise, or seem unaware of the layers above and beneath the particular strata they work within.

This has happened to me several times (not always in interviews). Especially when someone asks about machine learning and I start the explanation with regression, they get pissed. Nothing shows that you are trying to jump on a bandwagon than expecting needless complexity in explanations.