> It is safe to assume

You are misinformed (or speculating) and spreading FUD.

> This data is not included in iCloud backup. That detail is included in the article.

The word "backup" does not appear at all in that webpage? Your claim is unsubstantiated. For these features to work, they must be running on iOS as well, for people who don't own a mac. Siri is used more on mobile devices than on desktops, generally.