Since the syllabus is written to correspond to a single class per a single semester, as opposed to other class resources that may be reused, it acts as an incredible time capsule into one’s class. This page states all the necessary record-keeping one should attempt to keep on their syllabi, including Course Information, Topics Covered, and Major Assessments.
If you have all these details present in your syllabus, it will be easy for those in the future to know what major events occurred in the class, when they occurred, and what total material students were exposed to. This allows different universities to compare courses across institutions, researchers to view trends in educational practices over time, and verification for any discrepancies that may come up after the course has ended.