> On the other hand, I genuinely do feel theory is really important. While not knowing the minutia of a tim-sort doesn't indicate that you'll be a bad engineer, not knowing the runtime efficiency of a sort can lead to some really awful code.

OK but why don’t these interviewers ever ask “internals” questions? How does a CPU works, or what the different levels of memory hierarchy are, what an interrupt request is, what is pipelining, what is SIMD, what is a GPU, etc. Or how about compiler internals, what are the different stages in a compilers, what are the different grammars and parsers, what is an AST, what is interpretation, compilation, bytecode, JIT, and how does it work? How about database internals? How is a database implemented, what is relational algebra, what is normalization, what is a data model, how do indices work? Similar questions can be asked about operating system internals, networking, floating point arithmetic, etc. In my experience, no interviewer has ever asked me these questions. And as an interviewer, I have consistently been disappointed with candidates’ inability to answer basic and relevant “internals” questions. Ironically, the algorithms and data structures questions that are commonly asked in interviews are outdated ways of thinking which do not take the underlying hardware reality into account (memory hierarchy and parallelism). It could be because a lot of these FANG(-like) “engineers” are themselves not knowledgeable to ask such questions. Or they are aware that new comp sci graduates are unlikely to really understand anything at a deep level, but all comp sci students are drilled on algorithms and data structures. If you are targeting a very specific age group (0-5 years experience) and want a standardized test then I guess asking CS201 exam questions in a job interview make sense. Companies prefer the 0-5yrs experience segment because they’re cheap, don’t have children, are easy to exploit, and they are easier to “mold” into your corporate culture.