The only markets Linux doesn't Dominate are the Desktop and console space. The only thing holding back Desktop domination is Microsoft and it's vendor lock-in strategy. It says a lot when Microsoft has to use the power of their purse in order to maintain their position. Even Linux dominates in the IoT space with ~80% of the market, despite Microsoft having to make Windows IoT free.
Microsoft does not see Windows as a product since Ballmer left. It's more of a liability, because you cannot sell it twice, and you cannot sell a Windows subscription. Windows still makes them just 10% profits, but selling cloud servers and office suite nets them 60% of their profits.
Microsoft IoT is not even a thing, the power of Linux IoT is that you strip everything from your kernel until your system runs on 32 MB RAM.