From Joe Bower, a good, straightforward summary of most of the reasons not to grade learners, and some sensible suggestions about how to largely avoid using grades etc within a system that requires them. Though situated in a face-to-face school context, this very closely matches my own views on the subject and the methods I use to get around a system that is built on grading.
Address of the bookmark: http://www.joebower.org/2014/03/heres-my-chapter-from-book-de-testing.html