I spent 20 years writing & running various IT projects, using tools from various big name companies. They always had bugs (I anded up contacting the source developers of compilers, databases, GIS's, etc). Without a solid understanding of both OS & compiler theory, I would never have been able to identify the bugs, either for workarounds or to actually persuade the people that there was something wrong with their code. Did my bosses care? Well, I did keep getting projects, and raises, so I guess so.