Composers also didn't start using barlines (for the most part) until sometime in the 17th century. But they did use time signatures -- in other words, they'd tell you what the meter was, but you had to figure out for yourself where you were within that meter. And sometimes that earlier music comes out better if you read it from a copy without the bar lines, too ... but yeah, it's a real problem if you get lost or lose count halfway through.

JZG