Students divide up the work, write sections of the paper, and everybody in the group gets whatever grade the paper gets. In most disciplines, as a matter of fact, professionals write collaboratively. Grade the whole and not the parts. For example, with reading notebooks, you don't write many comments and you don't grade every entry. When faculty members realize they have permission to look at writing this way, when they can be convinced that students can write without overwhelming teachers with papers, then they are willing to use more writing in class.
Some faculty members are very dismayed when they see misspelled words and comma faults.
But that's not what bothers most of them. Most faculty members are bothered by faulty lines of reasoning, the lack of examples or support, by poor organization. Students are unpracticed in translating thinking into written form. So practice helps. A mistake I think teachers often make is that they don't think about what writers need to do when they write.