While I agree it isn’t easy to create great balance, the extreme outliers usually come from very few moving parts that are outright bugged or working in unintended ways. Those would be relatively easy to adjust.
Creating perfect balance, where 40 moving parts contributes to 1 build being twice as good as another, and changing any of these parts also affects 100 other builds, sure, that is a challenge.
The issue here for Blizzard isnt figuring out how to nerf a broken SB build.
It is them being afraid to apply that fix.