I'm no specialist but I'm inclined to disagree, for me it's the difference between the ability to run an arbitrary binary and the ability to read/write an arbitrary filepath

They are imaginary paths in the bash executable. They aren't usable outside it. Thus the netcat analogy.

Anything you can do in telnet or netcat can also be done in python, perl, ruby. One of those is likely installed, most probably python.

And if you think about if all applications where using files for communication blocking one program from the internet would be as simple as a chmod.