Currently, Grading History (How do I use grading history in the Gradebook? ) is completely unavailable in course sites over a certain size (around 100 students, in my observations). However, these large sites, generally with multiple teaching assistants and graders, are the ones that would benefit most from a log of who entered any specific grade.
At my university, we offer a very large number of courses that exceed the current capacity of the Grading History feature. Canvas adding support for this functionality in large courses would provide significantly increased transparency and accountability for our grading process and for instructors of large courses.