Its probably partially gatekeeping. "I had to invent a unique sorting algo in this interview so you will too".
But also, its a good measure of someones ability to take an abstract problem and solve it. Lots of mini events in a LC problem to critically think. Like you said, we need a filter and its really easy to use LC to be that.
That said, I've worked at fang with co-workers who had trouble using iterators or properly assessing complex Boolean logic (and I'm not talking about needing de Morgan), so sometimes LC skills are needed on the job. So getting a signal that "this person can't write loops" means "we don't trust this person not to write an infinite loop", however rare that day comes.
There's enough programmers who want FAANG jobs and its easy enough to apply and the pay is high enough that you should be free to gatekeep by someone who understands intro-to-java level data structures and algos. Maybe leetcode-hard is unnecessary, but easy should be doable.
But also, its a good measure of someones ability to take an abstract problem and solve it. Lots of mini events in a LC problem to critically think. Like you said, we need a filter and its really easy to use LC to be that.
That said, I've worked at fang with co-workers who had trouble using iterators or properly assessing complex Boolean logic (and I'm not talking about needing de Morgan), so sometimes LC skills are needed on the job. So getting a signal that "this person can't write loops" means "we don't trust this person not to write an infinite loop", however rare that day comes.
There's enough programmers who want FAANG jobs and its easy enough to apply and the pay is high enough that you should be free to gatekeep by someone who understands intro-to-java level data structures and algos. Maybe leetcode-hard is unnecessary, but easy should be doable.