Not that, but because developing synthesized virtues is extremely effort intensive and not very likely to be in character for NPCs, we need SOMETHING for the common civilian, and Combined Virtues for everyone simply takes too much effort to feasibly implement as a 1:1 project, while at the same time the very nature of combined traits means that broad spanning efforts to encourage them don't work as they oppose and support themselves. You could encourage patience or wroth culturally with relative ease, but you can't encourage Eye of the Storm the same way because the components are inherently contradictory.
Psykers, sorcerors and support staff for those can get the full dedicated effort to program them for balance, but it has to be done starting from childhood to get anywhere soon.
For everyone else, we need a broader cultural indoctrination.