When you look at other calibers, there usually aren't a wide range of twists, and a wide range of bullet weights. Take .22 LR rimfire. Most bullets produced are either 36 or 40 grain. I am reasonably sure there is just one twist rate traditionally used.

With .223 or 5.56 you have bullets from 40 grains to about 90 now. And 4 to 6 commonly used twist rates. Lots of variables.