Map Rank already can tell you who you have defeated. It isn't in list form, it's in the form of an icon next to the person's name when you are looking at games pages. So, you can tell who you have beaten for what medal.
And, I think those medals were given retroactively. Defeats prior to the medal count because they can be calculated. I thought that the only one that wasn't give retro was Random, which was coded differently prior to the medal...
Anyway, I'd like to be able to know who I won with easily without having to make my own list.