My understanding (I believe detailed in the article) is that Debian, at least, chose systemd because they were forced to if they wanted a reasonable default GNOME experience for their users. If they hadn't, GNOME would have been missing some features that would have been obvious and jarring.
You can certainly argue that they made the wrong call there, and that they should have pushed back (though arguably by the time Debian got there, that ship had already sailed), but "chose systemd voluntarily" is an incorrect simplification.