My first Linux installation took place circa 1992, I pulled my hair out for a month or so while I was trying to figure out how to install this very interesting and FREE operating system.
I considered myself an intermediate level user who at this point was trying to learn how to program using the C programming language. Why not C++? At the time all the "beginners" books assumed that you knew the C programming language.
I was reading an article somewhere, probably in the now "merged" C/C++ user's Journal, that introduced an operating system that was "built for programmers by programmers". Needless to say, the best place to learn how to solve coding problems or learn about coding was to look at working code.
A whole operating system with the code! Perfect.