I did a review of someone's code submission once where they pretty much wrote a bespoke JQuery implementation to handle the super-complex task of incrementing a number in a div when a button is pressed. I don't think they got the job. I felt a little bad for them, but a valid part of those coding interviews is "Will this person go off and do something crazy like write their own half-baked React instead of just using React?". Showing that you know how to write code as simply as possible is a big plus.