Windows is not way behind in scalability
That might be true however with their move to charing per core will make scaling it up an awful lot more expensive.
Then there is the long awaited move to OS Subscriptions. This will in all likelyhood piss a lot of users off royally.
Things don't look good for the guys from Redmond.
Note that I didn't even start on the well trodden ground here that is the hate for Windows 10.