Considering “the Linux system” is literally anything you throw on top of the kernel called Linux, it can be a development environment or anything you want it to be.

Yeah I thought about the same thing when posting, if anything it would have to be the the combination of tools available on Linux. Like GNU binutils, GCC, GNU emacs, GDB, Git. But that's how I remember him saying it. Either my memory is wrong, or he just wasn't that precise in his language.

But I think part of the appeal of an IDE is how all the parts integrate (the “I” in “IDE”) so a bunch of packages thrown together might not provide the same cohesive feeling.

I agree, it may not be what you want if you're looking for an IDE.

But, like me back then, if you're new to the Linux ecosystem, it's good to hear at least once that you don't strictly need to look for an IDE. And that you can instead use disparate CLI tools together, to make for an experience that some people end up preferring.