No, it's not actually about mastery of binary trees or other abstract computer science concepts.

leetcode is really a culture fit test and success points to the combination of "smarts", diligence, and conformity to some acceptable degree. It shows you have some baseline of familiarity with computing, can focus on an arbitrary task to pursue a goal, and will conform to an arbitrary process when it's asked of you.

Those are genuinely essential skills in an organization with 1000's of white collar professional workers.

More precise insight is gained when the test covers a binary tree inversion than that were it just some contrived logic puzzle like the LSAT or a critical reading exercise. The computer science bit does provide some signal and isn't completely arbitrary, but it's only a small part of what's being evaluated.

Among otherwise strong engineers, it tends to filter out the especially willful, prideful, independent, meandering, creative, and pragmatic ones. These personality types can be extremely valuable in some work environments and can still sometimes in through leetcode challenges, but spoil big bureuacratic systems like FAANG's when they're overrepresented.

The culture thing is huge. If you can’t find a few good leet code problems to enjoy, I don’t know if we are interested in the same field.

Having done a lot of interviews at least 70% of the time it’s filtering candidates who just aren’t very technical and haven’t studied computer science. The kind of people who hate reversing a linked list are the kind of people who haven’t touched a polynomial since high school.

It’s not unreasonable for a junior tech interview to expect you studied something like CS or EE. It’s a blessing that our field is open to all to give it a shot, but if that doesn’t describe you - you need to recognize that there is effort and study to fill that background.

"Leetcode" style tests were probably good when almost no one did it.

Now it selects for the very very very bad trait of high ambition and knowing to play the system.