This was one of the most eye-opening truths of the industry revealed to me when I started interviewing candidates. There are so many software developers, even with long histories of well-known companies on their resume, who just cannot write code. Even Fizzbuzz. Even "write a for loop with an if statement" type problems. Under pressure or under no pressure. On a whiteboard or on a computer. This has been shockingly true about a pretty consistent percentage of candidates for every company I've worked with as an interviewer for 25 years.

This is why we have leetcode and Fizzbuzz. There are simply too many phonies applying and counting on their charm and charisma to get them the job, which sometimes works when you don't make candidates actually demonstrate their skills.