As a blogger who makes similar assumptions, I think we depend on how a lot of us from that time "grew up" similarly. Sockets came to relevance later in my career compared to everything else listed here.

That might be part of it, yes.

As someone younger, ports and sockets appeared very early in my learning. I'd say they appeared in passing before programming even, as we had to deal with router issues to get some online games or p2p programs to work.

And conversely, some of the other topics are in the 'completely optional' category. Many of my colleagues work on IDEs from the start, and some may not even have used git in its command line form at all, though I think that extreme is more rare.