The article's premise is that it seems like nobody in Indonesia speaks Bahasa Indonesia well, because it's always a second language. I can't find a good reference right now, but I think that's wrong. I'm under the impression that in Jakarta and the surrounding areas (probably tens of millions of people) Bahasa Indonesia really is spoken as a first language. I think this area has historically been Malay-speaking anywa…
In fact, it's the use of regional languages like Sundanese which is diminishing. I could really feel the skill and the vocabulary range of even the native Sundanese are worse than 10-20 years ago. Lots of mixing with Indonesian vocabulary without knowing the Sundanese words.