I'm Finnish myself, and have studied English, Swedish, German, Chinese, Japanese and now a bit of Korean, so I understand your point about differences between languages.

It seemed to me like the point of the article was that your communication is at its most efficient/natural in your native language, instead of English for example, if it's not.

I just thought it was obvious.

Well i think you're quite wrong to put all languages on the same level here.

Every language is someone's native language, so they're on the same level as far as that point is concerned.