Why did early printed editions often preserve inaccurate versions of classical texts?

Early printed editions of classical texts, known as editiones principes, often preserved inaccurate versions because they were based on manuscripts that were already in a textually debased condition by the 1470s.1

During the late medieval period and early Renaissance, the prevailing attitude toward classical texts shifted from a tradition of faithful reproduction to a more subjective approach. Scholars, copyists, and readers—whose roles were often indistinguishable—frequently corrected texts freely and arbitrarily to make them more readable or to suit their own sense of elegance. Because these subjective, often erroneous modifications were common, the manuscripts available to early printers were frequently corrupt.1

Furthermore, early printers performed very little rigorous editing. Those responsible for overseeing the production of these first printed editions generally limited their efforts to superficial improvements rather than engaging in systematic textual criticism or investigating the sources of the texts. Consequently, these early printed books served to propagate and solidify the errors present in the debased manuscripts from which they were copied.1