In your last two years of undergraduate studies, you are typically taking upper level courses required for your major, or electives. If your professor submits a grade to the Registrar for you for a particular course for which you were registered, you get a grade you get the credit hours. Only you and he/she know if you ever attended a class or did the course work.
So, if several professors are submitting grades, they can probably cover all of the courses needed for graduation and if none of them require that you attend class or do the work, you sail through without ever meeting any of your classmates. Is this what happened? Hard to say, but the possibility of collusion adds fuel to the fire.
I bet that was rare or never in the days before the modern online courses. Obama is %100 fraud.