I'm not saying those things don't matter, or that it's not possible that you can overcome some algorithmic complexity just by brute forcing it with a smaller constant. I'm saying that it is exceptionally rare that you are ever in a situation where you can go "oh I have these two identical pieces of software, let's just pick the one that uses the efficient language". Really, it comes down to this question: "this code is slow, what should I do to improve it?". The answer is usually "fix the time complexity somewhere or do less work" and it becomes good enough. Maybe in some isolated cases I might rewrite a bit of it in a different language if appropriate. When I say "time complexity dominates footprint" I mean that most of the code changes I make along the lines of changing something to take "100 ms → 2 ms" where the other language would be "25 ms → 0.5 ms" but you can see why I would not say that the language dominates here.