For my crimes (looking at LinkedIn...yes, I know), a point I cannot stress enough for those who MSFT refers to as "early in career":
Learning the trendy thing without developing a parallel skill in the fundamentals will *always* catch up with you. Every time.
You *do* need to understand the platform below you.
Really.
*Really* really.
The way this plays out over a career is subtle but powerful. When those around you understand you to be a lightweight, or to "only know X", it will eventually cause them to refer you for fewer positions. Doors will remain closed that you might not even perceive. In moments of change, peers will not look to you for guidance.
All of that adds up.
Now, we all operate in different levels of the stack more-or-less, and a constant truth is that there will always be a higher and a lower level adjacent to what you are comfortable with. That's OK! It's natural. Don't let it get you down.
But also don't let it become a crutch. It's *necessary* to begin to grow an appreciation and understanding of the terms of debate in those layers as you progress. They're not "your" layer? OK. Cool. But you must become conversant in 1-2 above/below.
No, you don't have to do VHDL or etch chips or rebuild a crimp your own network cables if you don't want to. But if you work in browsers, you'll need to learn OSes and something about web development.
If you work on the web, you'll need to learn a lot about browsers and something about what designers are struggling with.
And if you're a designer, you'll need to learn about your medium (web development) and content design.
@slightlyoff Agreed, and this paradigm needs to be applied in other axes as well. Work primarily in C#? You should know a bit about Visual Basic (higher) and C++ (lower) and have an inkling of assembly (much lower). If you only know one layer, you'll inherently limit yourself.
