Every successful, real-life application required solving at least one really hard problem. This hard problem may only look like 1% of the application, but if it

Every successful, real-life application required solving at least one really hard problem. This hard problem may only look like 1% of the application, but if it does not get solved, the application would have failed. That 1% requires you to build something of a similar level of difficulty as rolling your own relational database system. At least one guy has to be able to recognize the problem and to solve it. Otherwise, the other ones won't be able to build, support and maintain the remaining 99% and won't have a job at all.