As someone who works at MSFT in the Azure space I can tell you that the statement of "Who chooses to use Azure? Mostly MS shops" is inaccurate in my experience. Of all of the customers I've worked with, most of their architecture is at least 50% linux/OSS, typically more like 75%. I've honestly yet to see a customer moving to Azure who has more than 50% Windows based systems. Almost everyone I've worked with only uses Windows Server for their SQL Server services, outside of that it's RHEL, CentOS or Ubuntu.

With that being said, the typical appeal of Azure (and likely other cloud providers) are the PaaS services. Those typically do have Windows VMs sitting behind them, although we are starting to make Linux an option on most of those.