They do produce plenty of false positives - just not "you hire an idiot" kind. You will hire a person completely unsuitable for the actual job, but is good at leet. Issue is not the lack of intelligence. Issue is not being software engineer despite being good at algorithms. Or not being good at whatever your position requires.
I do work in a team where majority was hired by puzzles of sorts. All of them are smart. They are not software engineers and it shows massively.
I do work in a team where majority was hired by puzzles of sorts. All of them are smart. They are not software engineers and it shows massively.