This is probably completely apparent to anyone who's had to learn an ancient language (4 years Jesuit high school Latin can I get a qui qui?!) --- to understand ancient Latin you need to learn the idiom, not because the Romans were overly fond of cliche, but because they were speaking in a different historical context in which their audience could be expected to understand that "nut" was synonymous with "toy", or Greeks could be expected not to track dates on calendars.

So just as reading the simply Yacc grammar for MRI Ruby is not a particularly great plan for mastering Ruby, learning the rules of grammar and memorizing individual vocabulary words isn't going to give you convincing conversational mastery of a spoken language.