Why accuracy is important when preparing text?

In the context of formal schooling, accuracy is important when preparing a text for the sake of receiving an Excellent score when the text is graded. In more general terms, preparing a text for public consumption, whether in print-form or online, should be accurate so that one's claims are taken seriously and can have a real effect upon readers. In all cases, there are clear moral grounds for working to make one's written work (of whatever sort) appropriately accurate.