I've done everything from hardware design to drivers in (many flavors of) assembly to large COBOL programs to C++ monstrosities to async webbish APIS and websites and that's why I can jump in at any level if needed. Usually, I just see how the pieces go (or could go) together better than anyone with the kind of "focus" recommended in this article ever could.
I agree, maybe you need to do this early on to remain employable, but it's a self-defeating long-term strategy in a fast and always faster moving industry.
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