Why does `find` have the tests `-anewer` and `-cnewer`, but not `-mnewer`?

(This is more a question out of curiosity and less a present problem that needs to be solved) I recently learned more about time-related tests in GNU find, and something caught my eyes: With files, you have three types of timestamps: access for when a file was last accessed, modify for when the file's content was last modified, and change for when the file's inode was last modified (by renaming the file, moving it to another directory etc.). So accordingly, there are three different types of time-related tests in find. For example, you have -atime, -mtime and -ctime. You also have -anewer and -cnewer, but as far as I can tell there's no such thing as -mnewer. Is there a specific reason why there is no -mnewer test? Has it just not been implemented yet? Did it exist once and has been removed? I'm basically just curious. I've looked into this with a fairly recent version of find, version 4.9.0.