Coding interviews have gotten out of control. Most of the people giving the coding interview couldn't pass it themselves. Even worse, the people who can pass these tests only do so by memorization--once they are hired, many are not competent Software developers.
In my opinion, it's infantile bro culture hazing and feelings of inferiority. Oh, you can't traverse a binary tree using Breadth-first search in aarch64 assembler? You obviously aren't qualified to work on our web application.
I've applied for front-end jobs and get asked some C.S. puzzle, to do something no front-end developer has ever needed to do (unless they wrote the one module everybody else uses).
And yet, it's not like I couldn't grok that if I needed to... just pay me and I'll figure it out, no problem.
The difference between me and the applicants they are filtering, is that I can both learn and implement w/e algorithm, in any language you want. Want proof? Just look at all these other algorithms I learned and wrote.