I've worked at startups for more than 20 years and I still fail these stupid tests because I refuse to "cram". And that's fine. Those are bad fits for me anyway - I've been a CTO, built and launched multiple companies, managed teams, worked well in teams, etc. But I am still treated like a new grad in most of these interviews.
I failed to implement a LRU cache fast and clean enough in one of these interviews. How many statups need this? I haven't done that since the 90s. And I fully understand how someone can look like an idiot for not being able to do some these tasks instinctively when they may be so recent in your mind, but if you never use them at your job, what's the actual point here? It's like hiring an architect based on their slide rule skills.
To me it shows a lack of care given to hiring in general. At best it reveals workers that will throw hours at problems rather than thought. Mercenaries, I guess. But companies that hire like that tend to have highly complex code. And not because it needs to be complex, but because the company culture tends to focus on clever solutions above solving business goals.
I would rather hire and work with people who focus on breaking down problems and keeping logic and structure as simple as possible. Complexity is the enemy of progress. If there is one benefit of leetcode is that it finds smart people who can handle lots of complexity. Which is useful! But I would rather hire someone who isn't and can't, but can solve real world problems effectively and consistently. Wild concept, I know!