It's absolutely the case that some developer still need to care about those things, but by the time I started my career 20+ years ago, it was possible to make a good career as a dev who didn't know how to work with computers at an extremely low level.
Run it under dtrace, probably others as well.
My desktop today has 64 gigs memory, 12 cores. 10 years ago, it was 16 gigs, 4 cores. 20 years ago, it was 1 gigs, 1 core. 30 years ago, it was 16 megabytes, 1 core.
It was quite a lot of fun in my university final project to be developing on a 6502 (NES) in Assembly and find myself working in a very restrictive environment. Likewise, when I was working with a powerful microcontroller, but still only 2k of memory and 16k of flash and not being able to use some libraries I typically do. I was left having to reimplement stuff on my own for my own purposes.