Support for linux was there, since the very early days of Azure. But at the time this was clearly Nadella's baby. AWS was running away with market share, and Azure gained some decent marketshare, at one point they said 25% of Azure revenue was on Linux, this was about 5 years ago or more, that can only have grown to now. No one lays that credit to Ballmer.
Microsoft's documentation wouldn't even acknowledge the present of Linux, I kid you not, till maybe 2012 or so. For example, pathnames like "My Folder" (spaces in folder names) - which are a no-no on any kind of server code (leave alone the block letters). This was as someone pointed out, Gates, since he was the tech architect (and hated linux or feared it ). In a sense, Linux rescued Azure, and Microsoft. Quite ironic, today we see Gates smiling (cluelessly imo), but Window's is still not a good environment for development - be it C# (a fine language), or Web. My colleagues on Windows struggle to run any Python code - all you need to do is git clone, followed by Pip install - that's still a challenge comparatively on Windows.
