As a hiring person I've interviewed great engineers with cool side projects who just weren't a good fit for the particular role I was hiring for. But also famously "I created homebrew" didn't get him a job at google. I've never had to use binary trees at work. :)
I wonder what people would say if mechanics were tested for their understanding of mechanical engineering intead of how to do an oil change. That's what the emphasis on computer science knowledge seems like to me. It has no bearing on whether I can style a button or create an API.
