I'm just not sure how it's possible to have any API committed to memory these days, though I agree that if one picks a small number of dependencies as core tech, one stands a far better chance of doing it and will realise better productivity outcomes than someone who compulsively includes every 30-line $PITHYNAME.js novelty to hit HN and GitHub.
Still, I grew up writing backend C in Linux environments, focusing heavily on socket programming, protocols and systems generally. I cannot help but feel that rapid development was a lot easier back then, and coding felt more rewarding. Part of that is definitely age; I'm 29 now, been writing C since I was 10, and started to feel consciously "burnt out" on coding around 20. (Basically running on motivational fumes ever since.)
However, there's more to it than that. C had a small and generally static standard library that one committed to memory easily with a little experience. Sure, one had to consult man pages from time to time for system calls, but in the grand scheme of things, writing code was a very original exercise, since so little could be taken for granted. That's why, even though I had to write 10x the lines of code, with my own lists and hash tables (notwithstanding GLIB etc.), I felt massively more productive after a coding marathon in those days.
I really feel that the practice of programming has shifted radically in its intellectual content since then. Primarily, we're wiring together prefabricated Lego blocks nowadays; when I write code in modern languages, I've got 27 browser tabs open and seem to spend 95% of my time looking up the fine points of how this Lego block connects to that one. Java is the archetype for this, but it happens even in more terse, expressive languages. Clearly, there are some productivity benefits from all this, being able to develop at a higher level while taking for granted many data structure primitives and wrappers, and I'm not blind to that. Still, it seems like the real art these days has shifted to adroitly and dexterously figuring out new APIs and libraries.
And there's so many of them! Verily a diarrhoeal explosion of APIs, libraries and dependencies. Even if you're impervious to the latest fads and fashions, the technology is shifting rapidly from year to year, and with it, entirely new documentation, methodologies, reference manuals -- an entirely new skill set, practically.
So, I'm hard-pressed to imagine how I'm supposed to ingrain APIs into motor memory when they are so numerous, expansive, and ever-shifting. Overall, I feel that my productivity as a programmer has declined considerably, even if the overall efficiency of lines of code has gone up. Pragmatically speaking, I'm not sure I'd trade in the overall productivity gains of all the abstraction for the halcyon era of C programming, but I definitely find it challenging to motivate myself to code when the primary skill set seems to be in looking things up.