I think that students should be allowed to miss as many courses as they want. They’re paying the tuition; if they want to skip class and fail, they ought to be allowed to.
On the other hand, a student who failed because he never went to class has no right to bitch—when I was teaching, I officially had a “no more than 3 unexcused attendances” policy but I didn’t grade on them—unofficially, it was a “skip as many classes as you like” policy—but I kept attendance records, which saved my butt on every single F I gave. (“See here where it says I reserve the right to lower your letter grade by one letter for every class you miss after your 3? Well, I didn’t have to do that, because you failed every test and turned in no homework, but between that and your attendance the grade is justified.”)
That said, the policy needs to be stated on the syllabus. If the policy is strict, and you don’t drop the class, you are responsible for complying with it.