Is this really a common problem?

I received an email from my professor today.  (No, not the one I am seeing, the one who is teaching my class!)  He was basically trying to get the point across that the first class was crucial, and that if we missed the first class then we should drop the class entirely and retake it some other time.  That what we learned in the first class is the basis for all quizzes and tests for the rest of the semester.  What I want to know is, is this so often a problem that a professor has to remind his students to come to class the first day?!?!?  Because I just cannot imagine missing the first class with no indication of what the professor is like and how he views absences, and no one you know to pick up notes for you.  Very strange.  Makes me feel old somehow.