It may not have always been the case that every noun required a count-classifier; in many historical varieties of Chinese, use of classifiers was not mandatory, and classifiers are rare in writings that have survived.
Every noun required a count-classifier. This may not have always been the case. Use of classifiers was not mandatory. This was in many historical varieties of Chinese. Classifiers are rare in writings. This is in many historical varieties of Chinese. These writings have survived.