the "good answer" was already acknowledged, the "real-world scenario" answer was accepted.
the second part ("what if we wanted to build it in-house") is purely hypothetical to gauge how the interviewee would approach the specific technical challenge (shedding some of the "real-world" constraints so that the focus is technical).
if they again say "well that is dumb i would just use sheets", that is absolutely an interviewee problem.
If they are a dime a dozen, then it becomes their problem. Whether or not they care it's their problem depends on their circumstance.
>it becomes an intervewing problem because you're wasting both you and their time.
how is it a waste of time to ask a technical question in an interview?
>If you have an excellent candidate [...] If they are a dime a dozen
how do you determine if they are an excellent candidate or an average one without asking any technical questions in the interview?
>Whether or not they care it's their problem depends on their circumstance.
care about getting the job? why would they interview if they didnt care about getting the job?