Interestingly, it looks like some of the "bad examples" are precisely the kind of things ML would produce. Others are what non-native speakers would produce (starting with "あなたは" to translate a sentence starting by "you").
I'm sure some translators were using ML before it was integrated, and those guidelines are here in particular to tell them about those problems.
Also, ML is now really good to translate between European languages, but Japanese is very different in its structure so ML from English to Japanese is not as good. I'm sure some people who only know English/French/Spanish/German saw that ML is pretty good, and don't realize that for some other language it just doesn't work.
> Also, ML is now really good to translate between European languages
As somebody who has to regularly bear "German" machine-translated UIs and manuals that originate in English, I can only say: No, it's not. It's atrocious.
I'm sure some translators were using ML before it was integrated, and those guidelines are here in particular to tell them about those problems.
Also, ML is now really good to translate between European languages, but Japanese is very different in its structure so ML from English to Japanese is not as good. I'm sure some people who only know English/French/Spanish/German saw that ML is pretty good, and don't realize that for some other language it just doesn't work.