You have to look at the customers. If you push for Linux throughout your organisation and you got hit with a linux zero day, it's your fault.

If you use MS, then it's Microsoft s fault, you won't be blamed because almost everyone was exposed to it and you got hit.

These companies also have older workforce who are used to windows and the switch would be difficult. Yes I know some older users would be fine but that is not the majority.

It's similar to the "no one got fired for buying oracle" situation