Some believe that it's important to teach those things about computer systems first. To anyone who knows how the machine works it's pretty obvious why a primitive stack variable is uninitialized: initializing them would cost a store which would in most cases be pointless. People use C and C++ because they want all of the performance the machine has to offer, and usually more. Stuffing the program full of immediate value loads and stores would make it huge and slow. C++ is already cursed with enough pointless stores, for example initializing the buffer of a string just after resize and just before copying something else into the same memory. We don't need more of these things.

The author then goes on to complain at length about {} initializers in C++11, which everyone recognizes as problematic, and which has been partially fixed in C++14. This has basically nothing to do with the first part of the article.

And the big advantage is that when you understand those concept and pointers, there's no magic in other languages (value/reference parameters, objects, functions as first-class citizens)

C and C++ are horrible academic languages for other reasons - the original design is just too much of a hack to begin with, and then there's decades of legacy backwards compatibility with it in all newer developments. Syntax is ugly and inconsistent, doing things right is often harder than doing them wrong, there are many features and exceptions that are only there for historical reasons, and standard library is very eclectic in terms of what is and isn't included (from a modern perspective). But take something like Modula-2, and pointers aren't a problem.

But for a first language I'd want to use something like Python or Javascript or even a toy language. It simply needs to be something where some basic, high level concepts can be taught without worrying about the details.

It's not even really hard, just crushingly tedious and error-prone. You could also write all your programs on 80-column punch cards or with (1)ed, but why bother if there isn't some technical reason why a text editor isn't available?