[yodsanklai]

> I'm sure there's someone out there who knows a guy who knows a guy who can somehow ace Leetcode but can't write an efficient website backend

I don't see what makes you think a person who can ace Leetcode should be able to write an "efficient website backend". These are different sets of skills. You can ace Leetcode and not even know what a backend is.

> knowledge of CS fundamentals

Leetcode is not CS fundamentals. It's a small part of CS fundamentals. Besides, candidates aren't asked to show they know the CS fundamentals. They are asked to show that they spent more time practicing leetcode than the other guys.