According to the linked article, IIS has only 16% market share overall, and less than 11% of the top 1000 websites, so I'd say yes.
Outside on the open Internet I absolutely agree that Apache and Nginx are the default HTTP servers. I switched from Apache to Nginx years ago (with a few exceptions) as it just seemed as though I could do more with less with it and it made sense for me to standardise.
Similar to how Apple takes ~75% of the handset market profits, IIS takes almost all the profit in the web server market and is increasing revenues year after year.
It does quite well for itself given that the competition is fierce and free.
If you apply a set of criteria then that is the result.
The more interesting metric (though hard to quantify) is how much is earned with software.
http://www.zdnet.com/blog/stewart/adobes-q1-financials-show-...
I would think ASP.NET/C# would make the most profits in the dynamic web language space.
My point being that CF has a license, whereas Ruby and Python do not - which has little value in gauging success, a la IIS v Apache/nginx. (Ignoring the reality of open source Railo and Open BlueDragon for the moment)
They also both have licenses, but they don't charge money to obtain a copy.