I am a .NET developer, and I am trying to hire excellent, well-rounded .NET developers (hint), and I can tell you that it is non-trivial, specifically because many .NET developers are not particularly well-rounded, nor have the vast majority of them much experience outside the .NET ecosystem, nor more than a basic understanding of the technologies which underly the very powerful abstractions MS has built on top of them.

So I can certainly sympathize that someone who is building something that requires more fundamental knowledge might find .NET to be an effective bunny-filter.

I did stop reading the article when I got to "I'm sure .NET is a dandy language."