What about a 'teaching' OS/compiler/toolchain vs. the 'real' thing? e.g., a stripped-down OS kernel with minimal clean code optimized for teaching vs. throwing

What about a 'teaching' OS/compiler/toolchain vs. the 'real' thing? e.g., a stripped-down OS kernel with minimal clean code optimized for teaching vs. throwing someone into Linux source. or a teaching-oriented compiler vs. wading into GCC/LLVM? Teaching languages/OSes/compilers/toolchains (if done well) lower the barrier to entry while providing a conceptual transition path to learning 'real' stuff later on the job. Plus, the 'real' thing that we may be teaching in school now may not even be relevant in 4 years in industry when students get out into the working world, and they will have to pick up new languages/toolchains/etc. constantly on the job anyways. There is definitely a good argument for authenticity, but also one for paring down extrinsic complexity to illustrate core computer science concepts. e.g., try explaining parsing using full-blown C++ as a case study -- that seems pretty daunting. But one of these teaching languages (if done well, of course) is much easier to write parsers for.