SBMM is somewhat pointless if we don't know the map beforehand
Maps greatly affect the gameplay. They affect what perks each side should bring and what playstyle they should tailor the build to. They should also straight up not bring certain killers on certain maps because it's a complete waste of time i.e. Nurse on Hawkins, Blight on RPD, you get the idea.
You're not getting good data from a killer game on a map that actively works against their power. That's a test of survivor skill if anything.
Comments
I really don't want to see that as killer. Thing is that there is not much changes you can do as killer even if you know map, but survivors can do lot of changes to adapt wtih perks.