You can see the same thing in modern languages that are highly inflected, as Latin was. In English, much of the meaning comes from word order - a word by itself cannot convey its grammatical role in the sentence; instead, it needs other words to convey the grammar. In Latin, a single word can convey a wealth of grammatical meaning, implying its grammatical context more clearly than a stand-alone word can do in English. Highly inflected modern languages, like the Slavic languages (Russian, Polish, etc.) for example, work the same way, allowing people to leave out words in casual conversation without any resulting ambiguity.