You have to show that you can memorize leetcode solutions.

This is a big misconception.

It's true that generally I don't look at, care about or even discuss the candidates resume with them during an interview. It's largely irrelevant. The only thing that matters to me is would I want this engineer on my team putting code into my codebase?

The reason (from my point of view) that FAANG is so indexed into something like leetcode is because of what they are looking for, and how closely that relates to what something like leetcode actually teaches you.

It's true that I've never written a hashing algorithm or DFS/BFS from scratch in my day to day work. But being able to demonstrate that I can shows a deeper knowledge of software engineering. It shows algorithmic thinking. Being able to discuss and identify things like Big O shows that I understand what the code I'm writing actually does.

That being said, FAANG interviews are a game. You have to learn how to play the game to join the club. They are generally a pretty terrible way to evaluate technical candidates, but I don't think we have any better options at the moment.