This idea has been developed and deployed to Canvas
Canvas currently offers the ability to hide the names of students whose work is being graded, but it does not offer the ability to hide the name(s) of those grading an assignment. Faculty frequently ask how to hide the identity of the teaching team member who grades a particular assignment. This feature is especially important for courses that are co-taught and for large-enrollment courses with multiple TAs, who might be subject to backlash for grades received.
Currently, we advise them to use the Crocodoc annotations Text Tool in SpeedGrader to provide feedback, but this is not ideal. Sometimes student submissions have very little white space in which to place these annotations, and they can be difficult for students to find and read. And this significantly limits the means by which faculty and TAs can grade: bulk uploading graded files displays names, SpeedGrader comments display names, and comment annotations display names. Additionally, the SpeedGrader mobile apps do not currently include the text annotation tool, which means that graders who need to hide their identities cannot grade using mobile devices.
A much easier solution for instructors would be one that hides the grader's name (perhaps replacing the individual's name with a generic term like "grader").