Scenario B very rarely happens.

What actually happens is Scenario C - it doesn't arise from a top-down planner mandating it, it arises from middle managers (or their subordinates) further down the food chain each trying to grow their own kingdom, who all get the same idea at roughly the same time, and each build their own solution to the same problem.

During times of plenty, or if the top-level planner is only absent-mindedly managing that part of their org, the firm will be willing to tolerate these competing implementations, but during lean times, they cut, cut and cut and consolidate down to one winning solution.

A lot of corporate politics and strategy makes a lot more sense when you start looking at the personal motivations of the participants in it.