Earlier quoted context omitted.
Are you willing to stop speaking, reading, thinking, writing in English and use Mandarin? And what about the fact that some concepts and words are enunciated more succintly or clearly in different languages? I mean, you have the perfect example in front of you: why are there so many programming languages? Could it be that some language constructs are more difficult in one language vs the other? Why invent new program…
The reason we have lots of programming languages is because: 1. They're not that different. Once you've learned a few, picking up new ones is pretty easy. 2. They're much easier to learn than human languages. To answer your first question: I probably wouldn't stop using english myself, but I don't think I'd teach it to my children.
Thus to get my (and the article's) point, you need not just stop teaching it to children, you have to completely erase the underlying knowledge the language holds and start over in a new language. This is the point: you lose much more than what appears on first glance.
And concerning programming languages, I don't see how picking up brainfuck for example is easy, but someone still put the effort into creating it. Imagine a universe in which you'd have to solve every single programming problem in C. You could dream up all sorts of programming language concepts, but you could never use any other language than C. I bet you'd find that a bit boring and tedious...
Make no mistake, I'm not advocating for languages to keep their purity. I think it's a good thing they mix and borrow concepts and words. But I do find the idea of having one world language an utter absurdity.