Why should I?
I'll peg myself as a half-competent developer, the kind who codes everyday and can lose a weekend to a spontaneous side project. I am completely in agreeance that tool mastery is vital for enjoying and being productive in programming, I just have no concept, not from this guide, and not from many others, why Emacs is better for me than Sublime Text, nevermind why I should consider taking a year (an eternity in technological time) to master it.
And I realize that's a question that requires an unfair amount of trivial knowledge (e.g. the way I work and design)...but that's kind of the core concept for me...I feel pretty productive in ST3, I can sense the shortcuts and power tools I haven't taken the time to master and where they would help me, and for the most part, I design my projects in a way that fit the ST3 navigational flow...which I imagine is a side-effect of ST3's overall excellent design. In general, though, the bottleneck for me in programming isn't the typing of code or navigating through files, it's the sitting and thinking...rarely do I ever feel that ST's navigational functions cause me to lose context or concentration.
So all things considered, what value does Emacs bring me? Is it better in general programming situations? Or for ones in which a highly customized environment is needed? In that case, then fashion the argument properly...I would never argue that Ruby is the best language for all purposes, but I could certainly argue that it's a great contender for specific domains, and as a "glue" code.
Maybe the OP lists some compelling use cases further down in this document, but I pretty much stopped reading at this line, which gives me low confidence that me and the OP share the same worldview of how things work:
> No job ad will list Emacs as a required skill. That’s actually a good thing. It ensures that only honest technical guys exist in Emacs community.