I don’t know anything about the author, so just speculating here: assuming that the interview lasts 1h, it’s not realistic (nor fair) to judge the candidate’s answer if the interviewer has spent more than 1h to think about the problem and potential solution(s).
Interviewers have thought about the problem they propose countless of times (at least once per interview they have hold) each time refines their understanding of the problem, and so they become god of their tiny realm. Candidates have less than one hour, add to that stress and a single shot to get it more or less right. You’re not assessing candidate’s ability to code nor their ability to handle new requirements as they come.
I spend more time than my interviewees on the question to try to solve the problem every way that it is possible to solve it. If a candidate picks any of the solutions they pass. If they pick a solution I didn't know of they also pass (with flying colors) but I fail.
Interviewers have thought about the problem they propose countless of times (at least once per interview they have hold) each time refines their understanding of the problem, and so they become god of their tiny realm. Candidates have less than one hour, add to that stress and a single shot to get it more or less right. You’re not assessing candidate’s ability to code nor their ability to handle new requirements as they come.