I realize your question is rhetorical, but there are tons of people. Anyone new to programming, in a CS course that uses git, for example, would be familiar with basic git but many would be unfamiliar with the path (or on Windows).
I concur, but they need not stay unfamiliar with it. The concept is easy: When you type the name of a program and hit enter, I look it up in a list of directories to see the first one that contains a file with that name. That list is $PATH. Any programmer will have to deal with search paths and stuff at some point in their life, and probably very early on, when they'll want to run their own scripts.
I agree that most programmers will run into $PATH at some point, but why force an order on them? Maybe they just want to get started using things like fancy diffs provided through package managers like npm.
