Why are all x+9 different tiers? They are all really similar so there is no matter for the tier to vary so much(from C)

I dont think a lot of the stuff in the highest tiers deserve their spots. Excluding 3+5 and 4+3, the sums that result less than 11 are boring. The sums that result 10 are especially bad and 5+5 is the worst

Also, 8+7 is objectively S tier