Emacs lisp is something you can figure out a bit at a time: mostly you're writing 'snippets', rather than organizing some huge codebase where you have to know all the ins and outs.
You are right: Bit by bit you write tiny macros that do things you need or want. After 1/2/5/10/30 years, your personal macros compound to create real efficiency. I don't use Emacs today, but I do appreciate that the ecosystem is enormous and well-developed.
That said, to emacs' credit, it makes (1) extraordinarily easy. C-h k to see which function is being called by a given key-combination and C-h f to get to the source of that function makes it very easy to look at the internals of the editor and figure what I should setq in order to make the editor behave in the way I want.