This is super edge case, but if you were to for instance grant list_users and create_users to an unprivileged Role such as Subscriber when their Menu has already been Customized, it will automatically add the Users Menu Item without the need to go in and manually add it in.
I don't think this is exactly a problem, but in the case of Plugins/Themes adding Menu Items those do require you to add them in manually.
Suppose I'll mark wontfix and just have this logged here for informational purposes.
Edit: This was an example. Please don't give Subscribers the ability to make Admins, guys.