[Pharo-project] private instance variables NOT objects? (Wikipedia)

In the Wikipedia entry on Smalltalk, there is this line in the history section, 3rd paragraph, added roughly a year ago: "...Smalltalk-80 added [[metaclass]]es, to help maintain the "everything is an object" (except private instance variables) paradigm by associating properties and behavior with individual classes, ..." Is this one of those esoteric details that mere mortals are not meant to understand, or is this an error? Lawson