Hello Paul,
There is a similar function in Moodle, but it is not found in the places where users need it! Actually, I stumbled across your post looking for other Admins suggesting changes to the notes function in Moodle. Basically, what you are looking for is referred to simply as "notes" in the moodle documentation: https://docs.moodle.org/28/en/Notes
You can get to user notes by clicking on the user profile from the gradebook, then you need to select "notes" from the navigation block. Or from the course main page, you can go to course > participants > notes. The link to the notes function is not on the profile itself, but the node is created in the navigation block.
This is unintuitive and is something I am looking for a way to solve. I want to see the notes node anywhere a course facilitator would need to make a note, for example when marking an assignment with plagiarism, or if a teacher finds a student seems to be dyslexic or other pedagogical reasons.
I hope this helps.