100% interviews are about communication and demonstrating thought process; after going through some rounds of interviewing candidates myself, any candidate who can adequately explain what they're thinking and how they arrive at their conclusions will be able to demonstrate their skills much more thoroughly than 'just use Postgres'.

That being said, it's also on the ones giving the interviews to push the candidates and ensure that they really are receiving the applicants best. The interviewers don't want to miss potentially great candidates (interviews are hard and nerve-wracking, and engineers aren't known for their social performance), and thus sometimes need to help nudge the candidates in the right direction.