And, that's the biggest problem. Grades do not help students get better.
Students accept what is given. The grades promote mediocrity. Think about the
message... here is an objective, and you scored about 80% on it, which fits you
in about halfway in our class. There's no impetus to improve on the 20% you've
missed out in, because as many teachers have in their grading schemes, the
chance to make up the missed points takes away the consequences for missing the
original deadline. So, we can't have that, can we?