You always could. It's just that you had to hunt down the album in the iTunes Store in order to "Like" something. And it was not "laughably tedious", as suggested in the article; you just click the little arrow next to the track name in your Library.
Now you can "Like" stuff directly from your Library.
All they've done is replace that little arrow-button with a pop-up menu. It's a pretty small change, overall, it just makes things more obvious.
