For me "systems programming" is just low level programming. You do it when you need to access the hardware, when you need performance. It seems a lost art. When I learned Pascal, C and C++ during high school most of my peers were learning and using these. Until early 2000s most of the software facing end users was quite low level because there was no way around it, people needed software that was fast enough. Even if…
But ultimately words only mean what ever you define them as in the moment, so system can mean anything you want it to, so long as that meaning is conveyed to others needing to understand how you are using the word.