[Aperocky]

In my personal experience, this came down to hanging up there with all the algorithm and data structure knowledge but no idea of what implementation in real life look like. The majority of people that suffer from this is identified by the OS they use --- just like leetcode isn't 100% accurate, which OS you use should have no impact on the ability of people to program. But the gaps are significant and I've found that people who use Windows to (usually) be very behind on actual implementation of software (of course there are good programmer who use windows, but they're the exception in my anecdotal experience).