So, are you trying to hire someone who will make stellar contributions to your codebase or are you looking for candidates who are good at answering dumb questions?
Yes, plenty of candidates with otherwise amazing track records can't code comically simple functions (not dumb questions) together, with tons of help and hints and direction provided. They can't articulate their thought process, can't describe what they're doing, can't ask for help or get combative or aggressive or entitled.
The question is entirely not the point. It's everything else that is signal. Could I work with this person? Could I give them a task and have confidence?
You show up out of the blue with a task that isn't connected to anything the org does and with all the decisions made already. I cannot search the internet, but you do not explain why. You sit down across from me and stare.
In my interviews you can use the internet. I don't stare, I'm mostly taking notes and answering questions, either listening to the candidate explain things or explaining things. No decisions have been made. I describe a problem, we solve it together. Just like we might on the job.
Sadly, this rings true. In a non-whiteboarding context I’ve sometimes asked JS/TS candidates something that I originally though was a nice easy, practical sort of algorithm question: how would you find the intersection of two string[] arrays? Even with plenty of hints probably the majority don’t get beyond a nested loop (sometimes they progress to [].filter and [].includes, which just hides it).