I think the point here, is that when beginners start exploring what's out there in "professional" lands they'll quickly discover that they don't know Python at all, because they were using this primitive subset of a language.
I don't see why not. Plenty of folks learn on the job, including new languages, and the way things work out you might end up implementing some things sort of by kitbashing, knowing relatively little of the concrete details that you end up learning completely more later on. I do this all the time.
go, but that brings along its own set of bug bear problems
But after 30 years of programming, do I actually know C? Once I dig into C compilers, undefined behaviors, etc. I can also quickly convince myself I actually don't know C at all...
As an introduction language, I don't see why you would need to use decorators, generators or anything? You don't need to learn control flow, functions, variables, etc. You can perfectly write python without all the fancy stuff. In fact, there are quite a lot of data scientists who are paid to write python and don't know the first thing about concepts as seemingly basic as classes.