Here's the meat of my point. The correct answer when writing software is "use a library". The correct answer when answering an interview question is code with minimal dependencies.
Which can be paraphrased as:
"Here's the meat of my point. The correct answer when building a wooden shack is "use a hammer". The correct answer when answering an interview question about building wooden shacks is to make the hammer first".
"Performance under modern software development interviewing practices has a very low correlation with on the job performance."
Not using a library when you should have is a problem solved by a 20 second code review.